Talk:Greenhouse effect/Archive 1

How do GH's work?

Are there materials which are equally transparent at visible and infrared wavelengths? If so would a greenhouse made of those materials still work?

I think it would still work, because a big effect of a greenhouse (as opposed to the atmospheric greenhouse effect) is the suppression of convection, not just radiation.

I maybe wrong. Anybody know?

See the end of http://www.physics.lsa.umich.edu/williams/phys240k/units/unit19.pdf for an argument supporting the above.

(SEWilco 22:04, 15 Aug 2003 (UTC)) Bad link. From the comment below, apparently it is the Woods reference which is in the main article.

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I would say greenhouse built with different materials will accumulate heat at a different rate if the convection in both cases are kept the same.

I disagree with the conclusion made by the Woods' experiment in your link above. I think his experiment has a flaw that his two boxes are made of black cardboards. So as the walls of the box are heated by the sun from the outside, the heat transfer and radiated as infrared from the inside surface of the walls into the interior. Basically, the heat transfer by the cardboards overwhelmed the greenhouse effect. I couldn't believe such a flawed paper could be written by a professor!

(SEWilco 22:04, 15 Aug 2003 (UTC))

• It says the boxes are packed in cotton. I think this means the sun does not hit the sides of the boxes, so only the window is exposed to the sun.  ::* He's waiting for temp to stabilize, so he's depending upon radiation from the box to match what is captured. With the cotton insulation, heat can only leak out the plate, thus he's trying to measure the difference between radiation which can leak out of the two boxes.
• He states rock salt is transparent to the black box radiation frequency at the equilibrium temperature. A real world greenhouse has a lot of water vapor -- what frequencies does hot water vapor radiate? Is there a difference between temp of a dry and a damp greenhouse?
• He states there is a small temperature difference. Maybe that is significant but seems small in his experiment. What is the size of the boxes, and what is the temp difference for larger boxes? If radiation on one square centimeter causes small temp rise, does a thousand square centimeters also only cause that same rise?
• He doesn't state it, but I think he believes the rock salt panel has similar insulation behavior as the glass, so convection off the panels should be similar.
• Opening a box, like opening windows on a car, merely allows cooler/warmer air to circulate, and does not indicate anything about the greenhouse effect unless the total air temp is measured.
• Also if the glass "stops the longer wavelengths" then the glass is either reflecting them or is being heated by them -- the glass is probably hotter than the rock salt because of the heat being removed by the filtering glass plate above the rock salt plate, so the temp of the glass container is distorted by the hot glass panel (but this would skew upward the glass temp, so as he saw little difference the glass box would have been cooler without hot glass).

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(SEWilco 04:04, 20 Aug 2003 (UTC)) So, do greenhouses really block outgoing radiation or not? I find it hard to believe the Wood experiment is correct, or it would be a standard demonstration in every junior high school physics class.

CO2 lifetimes

158.169.131.14 wrote:

NOT correct. The lifetime of CO2 is in the order of FIVE years, not hundreds. If you don't believe me, look at http://www.icsu-scope.org/downloadpubs/scope13/chapter01.html. This gives some figures. The atmospheric reservoir of CO2 is now about 750 Gigatonnes. Photosynthesis uses some 100 Gigatonnes/year (both land and marine plants). Exchange with the ocean comes to another 100 Gigatonnes/year. Lifetime is the reservoir size divided by turnover rate. Work it out yourself)

First of all 158.169.131.14 it woud be a good idea to get yourself an account. Second, to put comments like that in the talk page (here) not the article.

Secondly, your calculation of the lifetime is too simplistic. What is of interest is the lifetime of a CO2 anomalty in the atmosphere, not the individual CO2 molecules. See Greenhouse_gas; http://www.grida.no/climate/ipcc_tar/wg1/016.htm. IPCC tar says the lifetime is "5-200" years (FWIW sar says 50-200) and no single lifetime can be determined. It refers you to ch 3 for the details but they are elusive...

Real green house

The paragraph in the section titled "Real green house" is the most stupid and unscientific statement I have ever seen. The foundamental principle is how the glass let radiation (e.g. ultraviolet, visible light) in and then after the energy is converted into another form (e.g. infrared), the glass don't let it out. The basic principle was dismissed by a ridiculous claim that, when you open the window the greenhouse won't work. Hence it was concluded that the greenhouse works on the principle of convection. Such conclusion is really laughable. When you open the windows, you introduced the convection that carried the heat away. It does not prove that the greenhouse works by convection, you can only claim that the greenhouse is ruined by convection. The better set of experiments is as follow:

• eliminate the radiation and conduction from the greenhouse

built a greenhouse with insultated, oplaque walls and roofs and see how the heat get in without conduction nor radiation.

• eliminate the conduction and convection from the greenhouse

built a greenhouse with doublepane glass and no windows and see how the heat build up without conduction or convection.

• eliminate the radiation conversion that is the main principle of greenhouse effect.

built a greenhouse as the last one, but coat everything inside the greenhouse with mirror surface and then measure how the greenhouse does not work when there is no infrared to trap by the glass.

The argument about the opening window is flawed because when you open the window, you are looking at a totally different system, instead of just the greenhouse's relation with the sun, you are looking at the greenhouse plus the surround air. If you want to compare the earth to a glass greenhouse, then you cannot open the window to vent the hot air, because you can put a giant tube that poke into outter space and pump the hot air away, you can stop the global greenhouse effect just like you open the windows of the glass house. On the other hand, if you can build a large enough greenhouse where its roof is above the atmosphere, then whether you open the window on the roof or not will make no difference to the temperature inside the greenhouse. Therefore the global and glass greenhouse work the same way except that the convection effect overpowers the greenhouse effect when you have a small glass house.

Kowloonese 23:10, 5 Nov 2004 (UTC)

(William M. Connolley 11:36, 6 Nov 2004 (UTC)) Well that was jolly good rant. Now go away and read: http://www.wmconnolley.org.uk/sci/wood_rw.1909.html Now notice that the same article is referenced on the page.

I was indeed referring to the flawed Wood's experiment. He wrote a paper, you don't have to agree, do you? Kowloonese 08:47, 8 Nov 2004 (UTC)

(William M. Connolley 09:28, 8 Nov 2004 (UTC)) He did the experiments. He built a non-radiative greenhouse. It worked just as well as a radiative one (as do modern plastic polytunnels which are mostly transparent to IR).

The argument about the opening window is flawed because when you open the window, you are looking at a totally different system, instead of just the greenhouse's relation with the sun, you are looking at the greenhouse plus the surround air. That's right. It is a different system. Exactly as a fanciful "pipe out to space" would make a totally different system: earth plus surrounding space insteads of just earth. In other words, the analogy in the article is entirely appropriate. Tannin 09:46, 8 Nov 2004 (UTC)

Scientific works are subjected to peer reviews. The Wood's experiment reads like baloney to me, though I am not his peer. What is the general acceptance of his conclusion in the scientific community? Anyone who has studied history of science knows that many convincing scientific theories were later proven wrong. This one is not even convincing. Why is his view stated like the gospel in this encyclopedia? It is definitely not NPOV. Kowloonese 21:34, 8 Nov 2004 (UTC)

(William M. Connolley 22:17, 8 Nov 2004 (UTC)) A peer reviewed paper definitely trumps your personal biases. What part of his experiment do you disagree with, and which of his results do you dispute. And please don't forget about the IR properties of plastic greenhouses.

I have a ridiculous argument that this analogous to the open window argument by Woods. Here it goes, prepare to laugh. I can prove that penicillin is not a cure for bacterial infection because if I cut open the patient's artery, the patient dies. The open window green house is as silly as this. It just does not make sense at all. Kowloonese 21:49, 8 Nov 2004 (UTC)

(William M. Connolley 22:17, 8 Nov 2004 (UTC)) Your argument is indeed ridiculous, but also irrelevant.

Origin of Name

How did the tern "Greenhouse Effect" originate?

A greenhouse, [1], is a clear glass structure in which plants are grown (thus, making it appear green from all the plants). The environment inside of such a structure is warmed because of the "greenhouse effect", which is that light goes through the glass, strikes the plants/ground warming them, and then the thermal radiation which would radiate back out is partially reflected by the glass. Therefore there is a net warming effect. (example picture: [2]) — Cortonin | Talk 03:00, 22 Jan 2005 (UTC)

I never stopped to consider describing the origin of the term on here. Do you think the article would benefit from a short summary of its etymology? — Cortonin | Talk 03:00, 22 Jan 2005 (UTC)

(William M. Connolley 12:05, 22 Jan 2005 (UTC)) Sigh. Why don't you read the page, the section "Real greenhouses"? Greenhouses do *not* operate by the GHE. Who first started this incorrect analogy would be interesting, though. And thermal radiation isn't reflected by glass, of course.

Yeah, it seems that section was based on a very short 1909 paper (which compares a medium which lets more NIR wavelengths in and more thermal wavelengths out, with glass, and then tweaks the setup until they come out balanced). Regardless, we have better experimental methods now with more modern materials, and an entire industry that works on just this. I fixed that section, and included three references: A textbook which discusses the mechanism, a website targetted toward laymen, and a research paper on modern greenhouse design where radiative transmittance is selectively controlled to regulate growing conditions. — Cortonin | Talk 19:40, 22 Jan 2005 (UTC)

(William M. Connolley 20:03, 22 Jan 2005 (UTC)) Read the Wood paper. It shows that a structure transparent to IR heats up just like one opaque to IR. To quote: This shows us that the loss of temperature of the ground by radiation is very small in comparison to the loss by convection, in other words that we gain very little from the circumstance that the radiation is trapped.. Those results remain valid. The IR properties of the covering have an effect, but a minor one. I am told (though I've never verified it) that many plastics used are in fact transparent in the IR region anyway.

You should reread it, in the first run the rocksalt enclosure got HOTTER. Then he places them both under glass and they both reduce until they are equal. What happens if he places them under two pieces of glass? It was clearly not a very thorough experiment, as his concluding paragraph states, yet far more thorough research has been done in the intervening 100 years which shows his conclusion incorrect. We have an industry designed around making enclosures that regulate greenhouse temperatures by selecting radiative properties. The plastics used are not transparent in the thermal IR region, usually only in the NIR region. They are selectively designed (based on climate desired) to keep thermal IR inside, as clearly described on the third reference I added. Please do NOT revert before READING the sources I added. — Cortonin | Talk 20:12, 22 Jan 2005 (UTC)

(William M. Connolley 09:30, 24 Jan 2005 (UTC)) Yes indeed, the Rocksalt encloser did get hotter. Which demonstrates quite conclusively that transparency to IR doesn't prevent warming. You added: However, convection can only act to bring the temperatures inside and outside of the greenhouse into balance.. This makes no sense: temperatures inside and outside *aren't* in balance: thats the point: its warmer inside.

(William M. Connolley 12:30, 24 Jan 2005 (UTC)) I've added some extra links. In case you have trouble finding the texts, let me quote:

temperatures in a greenohuse are not to be attributed to the absorption of long-wave radiation by the glass (Fleagle)

It has nothing to do with greenhouses, which trap warm air at the surface (Henderson-Sellers)

this phraeseology is somewhat inaapropriate, since CO2 does *not* warm the planet in a manner analogous to the way in which a greenhouse keeps its interior warm (that by Sherwood Idso, a noted skeptic, in case you're thinking this is some vast conspiracy)

The term greenhouse is somewhat of a misnomer... actual greenohuses work primarily in preventing the turbulent removal of heat... the emissivity of the glass panes to infrared radiation is generally insignificant (Cotton and Pielke, Human impacts on weather and climate (a generally mildly skeptic book)

You know why "skeptics" are the ones saying the point you're arguing in favor of here? It's precisely because by that same argument, more of the Earth's temperature is determined by convection than by the greenhouse effect, because convection is a more significant contributer than the greenhouse effect. And that's definitely true, as I have had comment about in that last paragraph. Similarly, more of a real greenhouse's temperature DIFFERENCE from the outside comes from the ABSENCE of convection, than from IR, but there IS still a significant contribution from IR opaqueness. Greenhouses do not heat up by convection supression. Measure the temperature of a glass room at night with no light, and will not just sit there and heat up because there is no convection, that would violate the laws of thermodynamics. Greenhouses heat up from the solar light which enters, and they gain additional heating over a completely transparent media from the thermal IR which glass is highly opaque to. Modern greenhouses are even made of materials specially engineered to select the amount of heating from thermal IR opacity (which clearly is only done because the contribution from thermal IR opacity IS significant). Arguing that the two are different phenomena because gardening greenhouses would be cooled off partly by convection if it were permitted is just toying with semantics, because the same thing applies to the global greenhouse effect. While you're at it, you could argue that gardening greenhouses function by an absence of liquid nitrogen being pumped into them, because clearly the right amount of liquid nitrogen would cool them off to the outside temperature. The argument would be the same. — Cortonin | Talk 19:12, 24 Jan 2005 (UTC)

(William M. Connolley 20:53, 24 Jan 2005 (UTC)) This is stupid. I've provided refs from a variety of atmospheric science sources showing that the term is a misnomer. Even if you happen to disagree with the science (though I don't undrestand why you do) you need to accept the wiki policy of (a) reporting the maainstream view and (b) no original research. Every atmospheric science text that thinks about the name conclude its a misnomer. I've never seen even one that says "people say its a misnomer, but it isn't". If you have a radiative physics background, thats nice, but totally irrelevant: wiki isn't here to represent your views (or mine) but what the science has written down. And whats written, time and again, is that the name is a misnomer.

Did you even read the sources I posted? Yes or no? If you did perhaps you would have seen a few sources that disagree with you. Allow me to quote from NPOV#Avoiding_constant_disputes:

How can we avoid constant and endless warfare over neutrality issues?

The best way to avoid warfare over bias is to remember that we are all reasonably intelligent, articulate people here, or we wouldn't be working on this and caring so much about it. We have to make it our goal to understand each others' perspectives and to work hard to make sure that those other perspectives are fairly represented. When any dispute arises as to what the article should say, or what is true, we must not adopt an adversarial stance; we must do our best to step back and ask ourselves, "How can this dispute be fairly characterized?" This has to be asked repeatedly as each new controversial point is stated. It is not our job to edit Wikipedia so that it reflects our own idiosyncratic views and then defend those edits against all-comers; it is our job to work together, mainly adding new content, but also, when necessary, coming to a compromise about how a controversy should be described, so that it is fair to all sides.

This is official Wikipedia policy, so it would be nice if you considered following it here. The statements I have added to the "Real greenhouses" section, I will stress, are documented, so your comments about "original research" are not related. The sources I have documented are ALSO mainstream, so please leave them, along with their description, as a source of further information.

In an attempt at compromise, I have placed both interpretations side-by-side. This should be acceptable, so PLEASE DO NOT REVERT IT. Have faith in the reader, and let the reader decide. — Cortonin | Talk 07:01, 25 Jan 2005 (UTC)

(William M. Connolley 09:41, 25 Jan 2005 (UTC)) For the moment, that will do as a compromise. I don't think it can last for ever, but I'm happy to give other people the chance to read both versions and comment.

Thank you. — Cortonin | Talk 18:47, 25 Jan 2005 (UTC)

To help ease your conscience, contemplate this explanation: Convection will only act to equilibrate two temperatures, so if there were no radiative imbalance contribution, then everytime the outside air was cooler than the ground, the greenhouse would be warmer than the outside air and ground, and everytime the outside air was warmer than the ground, the greenhouse would be cooler than the outside air and ground. Yet this does not seem to happen. This is such a "specific" result that it's very unlikely to find it documented, and it's too specific to be useful to the article, but it's very easy to derive the result for yourself (it would make a nice undergrad thermo problem). If radiative imbalance were not a contributer, and there was no atmosphere, then the ground and greenhouse would reach the same temperature by conduction. Then when you apply the atmosphere to the system, if the atmosphere is warmer than this temperature, the convection theory proposal is that it warms the ground but not the greenhouse, thus making the ground and atmosphere warmer than the greenhouse, or if the atmosphere is cooler than that temperature, it cools the ground but not the greenhouse, thus making the atmosphere and ground cooler than the greenhouse. Now this is clearly not how actual greenhouse temperatures behave, but that's because in actual greenhouses, there is a radiative imbalance which raises the temperature above that point. Spend some time thinking about the system I just tried to describe, and then hopefully you'll see. — Cortonin | Talk 18:47, 25 Jan 2005 (UTC)

Mr Connolley worships the flawed Wood's experiment and his flawed conclusion as gospel. I don't think you would be able to change his mind. See a few sections above. There were some debate that didn't go anywhere. Doing it all over again will not change a thing. Kowloonese 01:19, Jan 26, 2005 (UTC)

WMC, if you were to read the above more carefully, you might understand why the argument you're putting forth is physically invalid. The fridge analogy is this: The mechanism by which a fridge operates is by application of a heat pump. What you're implying is that the fridge operates primarily by suppression of convection, because if you open the door to the fridge it will be close to the temperature that it is outside. Obviously this is backwards logic. If you unplug the fridge, it STILL has suppression of convection, yet obviously all of your food will spoil. So clearly suppression of convection is not the mechanism by which the fridge operates. The primary mechanism is the mechanism which causes the temperature difference, and this is the heat pump (or in the case of the greenhouse, the radiative imbalance). Certainly the fridge WILL bring its temperature close to equilibrium if you leave the door open, but this is because the presence of convection undoes the mechanism by which the fridge operates. Similarly, if you place a toaster oven on high inside of a closed fridge (with a cord running inside), you will also find the inside of the fridge staying close to the outside temperature. Does this mean that a fridge operates by an absence of toaster ovens? Clearly not. — Cortonin | Talk 15:40, 21 Feb 2005 (UTC) If you want to do a proper experiment, take a greenhouse and bury it. Then there will be no radiative imbalance at all. You will find the temperature inside the greenhouse will be the same as the temperature of the ground, not hotter, even though there will be suppression of convection. Likewise, a greenhouse sitting on the surface fully exposed would reach equilibrium with the temperature between that of the ground and the atmosphere if there were no radiative imbalance. Instead, in reality there IS radiative imbalance, and a greenhouse can get hotter than either the ground or the atmosphere. And in fact, radiative imbalance is the only physically valid way that a greenhouse's temperature can exceed that of both the ground and atmosphere. This is elementary thermodynamics. The inside of a car cannot be hotter than the temperature of the surfaces it is contacting without work being done, and that work is done by a radiative imbalance. Anything else would violate conservation of energy, and yield a spectacular perpetual motion machine. — Cortonin | Talk 15:40, 21 Feb 2005 (UTC)

(William M. Connolley 21:39, 21 Feb 2005 (UTC)) I don't think you've understood this at all. The fridge analogy is irrelevant. The physics is: heat comes in (solar radiation). Heat is retained inside the GH, so it warms up, more than does the outside world. The question is, what is retaining the heat? There are two posibilities: that it is primarily the radiative properties of the glass (or plastic, or whatever); or primarily the physical-barrier properties of the glass. We know its not the radiative-barrier properties of the glass because (a) we can replace the glass by something transparent to IR; and it still heats up (b) we can open a small window (that does not strongly affect the radiative properties, but does affect the physical-barrier properties) and it cools down. So the important effect is the physical barrier that the glass presents to the movement of tthe air heated by contact with the surface.

If you replace the glass by something transparent to UV through IR, then the inside of the greenhouse will only be hotter if the temperature of the outside ground is warmer than the temperature of the outside air, because this is the only case in which the convection would cool the heating of the outside ground. However, this is only the case part of the time, as the rest of the time the temperature of the outside ground is actually cooler than the outside air, and in that case the greenhouse with the fully transparent material would be cooler than the outside air. Obviously real greenhouses do not do this, because there is in reality a radiative imbalance. It does not get any clearer than that. — Cortonin | Talk 02:39, 23 Feb 2005 (UTC)

That Wood experiment is seriously flawed, incomplete, and outdated. You should not rest so heavily on it. — Cortonin | Talk 02:39, 23 Feb 2005 (UTC)

(William M. Connolley 10:22, 23 Feb 2005 (UTC)) You should have a bit more respect for published research, and actually read it. Woods clearly states: When exposed to sunlight the temperature rose gradually to 65 oC., the enclosure covered with the salt plate keeping a little ahead of the other, owing to the fact that it transmitted the longer waves from the sun, which were stopped by the glass. In order to eliminate this action the sunlight was first passed through a glass plate. The inside is slightly warmer with rocksalt because it passes IR from the sun. This was then controlled for.

I think you idealize scientific literature a bit if you expect me to take a six paragraph paper from 1909 seriously which has conclusions which violate basic principles of thermodynamics just because it's "published". I read the Wood paper on a link you posted. First, the Wood paper itself ends with, "I do not pretent to have gone very deeply into the matter", which clearly he didn't. The "control" mechanism you describe there is a completely faulty control mechanism. Surely you don't think one piece of glass and one piece of rock salt is a control for either one or two pieces of glass (the paper is ambiguous as to which amount was used for the second arrangement, despite how critical this is, and is also ambiguous about the spacing between these plates. Are they on top of each other, or is there ventilation between them?). An incomplete experiment with a defective control mechanism from 100 years ago is hardly grounds for throwing out the conclusions of an entire greenhouse manufacturing industry worth of research. You should have a bit more respect for the standards of quality in science. — Cortonin | Talk 13:48, 23 Feb 2005 (UTC)

(William M. Connolley 10:22, 23 Feb 2005 (UTC)) For reasons that are unclear to me, you are attempting to insert text that directly contradicts perfectly clear statements in a large number of meteorological textbooks and the published literature with what amounts to personal research. You can't do that.

Basic thermodynamics is hardly "personal research". I make no claim to have invented the field. If you note the two sections in dispute carefully, you'll see that the section you are supporting has three reference links, one called "Bad meteorology" which makes an allusion to the Wood paper, one on your personal website where you present the Wood paper and selectively agree with some of his conclusions while disagreeing with his other conclusions, and another reference which simply references the Wood paper. Then you list three textbooks from the early 80's which I obviously don't own, and I'm not about to go purchase just to verify your claim that they say something about the mechanism of real greenhouses. Perhaps you could quote the precise and full text in which each of those three textbooks makes a claim about the mechanism of a real greenhouse. — Cortonin | Talk 13:48, 23 Feb 2005 (UTC)

In comparison, the section you keep erasing is referenced with five CLEARLY ACCESSIBLE and independent sources from a variety of locations. If you want to talk about something you shouldn't do, deleting something that clearly documented by replacing their conclusions with your own conclusions is something you shouldn't do, and I would kindly request that you stop doing so. — Cortonin | Talk 13:48, 23 Feb 2005 (UTC)

You seem to have either not read or completely not understood the descriptions I gave above which make it clear why convection suppression is not the "mechanism", and why opening a window in a greenhouse tells you nothing about the mechanism of its operation. If there is something specific which is unclear about those descriptions, please state what it is and I will try to make it more clear. — Cortonin | Talk 13:48, 23 Feb 2005 (UTC)

(William M. Connolley 22:35, 25 Feb 2005 (UTC)) I've now added quotes from two meteorological/climatological sources which say, with no qualification, that it is a misnomer. This is a meteorological subject. You should accept their expertise. I've also put a description of the basic physics on this talk page. If any of that is unclear, do let me know, and I will try to clarify it.

It's not a meteorological issue, it's a physics issue.

(William M. Connolley 21:15, 26 Feb 2005 (UTC)) Only in the rather meaningless sense that all the world is physics.

The function of a greenhouse is the domain of thermodynamics, not meteorology. The only arguments you have presented here is the Wood paper, which is a bad and incomplete experiment easily countered by the more recent and thorough examples I referenced,

(William M. Connolley 21:15, 26 Feb 2005 (UTC)) This is just wrong. The woods expt is good, and still valid. You have referenced nothing 1/10 as relevant. You're also conveniently forgetting the two direct quotes from met books.

And you're ignoring the physics. See the description below. You pretend to be all pro-science and act like you're fighting the good fight against anti-science, but when I present you with a clear description of the science you fall back to an obscure reference and a non-detailed quote from a textbook. Are you really interested in understanding the science, or are you just trying to be right? Conservation of energy is not an optional rule here. Work must be done to create a temperature imbalance, and in an insulated system that work is done by a radiative imbalance. — Cortonin | Talk 08:10, 27 Feb 2005 (UTC)

and the argument you seem to have made up that opening a window in a greenhouse tells you something about how it functions. The window argument is wrong. Adding an additional method of equalizing temperatures does not show the mechanism by which unequal temperatures were reached. The natural path of all things is to equalize temperatures (the second law of thermodynamics), and the only way to create unequal temperatures is to do work. The thing which does the work is the mechanism by which the item operates, which in this case is a radiative imbalance. — Cortonin | Talk 00:28, 26 Feb 2005 (UTC)

I believe WMC has confused which is the chicken and which is the egg. The term Greenhouse effect was a physical phenomenon way before the meteorologists borrowed the term to describe a global phenomenon in similar principle. Now the original term is redefined because the meterologists said so. The green house and the Earth would behave the same if the glass roof of the greenhouse can be theoretically raised above the atmosphere. But since no one can build such a big green house, a regular greenhouse will be overpowered by convection which is not observed in the global greenhouse. Kowloonese 06:05, Feb 26, 2005 (UTC)

More how stuff works

Vsmith, I see what you're trying to say in that latest addition to the thermal IR section, and there is value in trying to describe the mechanisms in more detail like that. But you have two aspects slightly incorrect in that description. First, you place an emphasis on the directional focus of the radiation, but it turns out when you do the math that the only things that matter for determining the equilibrium temperature is the radiation going through the gateway (in this case, through the glass). Second, you wrote "The amount of infrared radiation reaching the greenhouse covering is considerably less than the incoming radiation". This is incorrect, because with sufficiently insulating glass, the heat loss due to direct thermal contact through the glass and ground will be small, and the equilibrium temperature will be defined by the point where the radiative flux out nearly matches the radiative flux in. — Cortonin | Talk 10:08, 26 Feb 2005 (UTC)

Added heading above - section way too long - got lost navigating :-) Anyway let's see, about the first: ...emphasis on the directional focus of the radiation, it seems to me a homely example might work here, the sun shines through my south window in the winter (not so much today as it's cloudy) and strikes the floor. I put my bare feet on that illuminated spot and viola it is warm, I step a few inches to the side and it's not warm. Line up that warm spot, the window, and the sun - there is definitely directionality there - hmm. The non-directional warming or radiative heat transfer within the atmosphere is an important factor in warming the surface and objects on the surface. But that is mostly IR and you stress that IR don't get out through the glazing - well then logic implies that it can't get in that way either. So it seems the main energy source would be the directional short wavelength radiation from the sun - I think the term solar greenhouse implies that connection.

Yeah, that section was getting hard to scroll through.  :) As for the directionality, it is true that the solar radiation is directional, certainly. The blackbody radiation generated inside the greenhouse goes in every direction, and the fraction that is pointed out through the glass is actually a factor in the equations below, and shows up as a geometric component in the constant C (which is constant for each particular greenhouse), because the component responsible for balancing is only the portion which goes out through the glass, so this is the fraction that aims toward the glass times the fraction that goes through. But the geometric component is not the reason for the warming, since if you remove the glass it would be the same as the ambient temperature. — Cortonin | Talk 17:41, 27 Feb 2005 (UTC)

the second: I agree that given sufficient time, without input from the directional sunlight, equilibrium will be established via all those physics equations below :-) (and, yes I have read and at least think I understand what you are saying). However, the blocking of the convective part of that equilibrium seeking process by the glazing is the major factor in keeping the greenhouse warm for the short term until the sun shines again. The greenhouse doesn't reach equilibrium with the outside air because the convective path is blocked - and the sun comes back up hopefully long before the radiative and conductive processes (which keep on working) can equalize the temperature.

The IR absorbance is also a factor in maintaining this. Try it yourself on a cool night. Sit by a window with the curtains closed, and then with the curtains open. The window will block some thermal IR, but the curtains will block almost all, and this will make a noticeable difference in the temperature. — Cortonin | Talk 17:41, 27 Feb 2005 (UTC)

I'm well aware of this, the south end of my house, both stories, is glazed. The big drapes were quite expensive. I see agreement that glass is not opaque to IR or that conduction works quite easily through glass. I know that modern insulated glazing materials cut way down on this. However, you seem to be partly agreeing that the major factor retaining heat overnight within a typical old fashioned greenhouse is the lack of convection with outside air. Noting, of course that thermal equilibrium is not reached overnight by a good amount, assuming enough mass present for heat storage - otherwise greenhouses wouldn't be worth much. -Vsmith 00:46, 1 Mar 2005 (UTC)

Certainly if you had outside air flowing into the greenhouse, the temperature will match the outside temperature quickly. This is no different from leaving the refrigerator door open, which will cause the temperature inside the refrigerator to match the temperature in the room. And I think I typed a section which clearly states that within the thermal IR section. What you need to be careful to avoid, is you need to avoid saying, "opening the refrigerator makes it warm, so the refrigerator gets cold because the door is closed." Obviously we all know the refrigerator does not get cold simply by having a closed door. It just, for some reason, seems to be harder to convince people of this when it comes to the greenhouse, because they can't see where the electrical cord is running. If you want another analogy, does an oven get hot because it is a sealed container, or because there is a heating coil in it? If you allow convection by opening the oven door, it doesn't get very hot. So then what is it that makes the oven get hot? It's still the heating coil. — Cortonin | Talk 05:14, 1 Mar 2005 (UTC)

And I should probably add that glass is not completely opaque to IR, it's only partially absorbant. This is part of why the thermal glazings are helpful. What you seem to be searching for, is some sort of equation which equates the rate of thermal IR loss through conventional glass to the rate of cooling through an open window of a certain size. The size of the open window which would equate the rate of energy loss as thermal IR at night would vary for every single greenhouse and would vary as a function of the internal temperature of the greenhouse and the outside temperature. However, I'm not sure why you're looking for this relationship, because it doesn't tell you anything about how the greenhouse operates. — Cortonin | Talk 05:14, 1 Mar 2005 (UTC)

I don't believe I said anything about open windows or any refrigerator analogy. So I have no clue what the above paragraphs have to do with my discussion. Vsmith 04:29, 2 Mar 2005 (UTC)

I'm simply trying to find as many ways as I can to explain it to you, since you still seem to be not getting it. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

And finally, here's one for you to consider. If you park a car in a greenhouse, will the inside of the car get hotter than the greenhouse? Thermodynamics tells us yes. Do you understand why? Clearly it's already convection isolated from the outside world, yet it still gets hotter than the surrounding greenhouse. This is because the greenhouse reaches its greenhouse temperature, and then the inner parked car still has a radiative imbalance, forcing it to a higher temperature relative to its environment (the greenhouse). This so called "greenhouse-in-a-greenhouse" effect is used in gardening to heat water pipes within a greenhouse, or to place transparent plastic sheets over plants within a greenhouse to keep them even warmer. — Cortonin | Talk 05:14, 1 Mar 2005 (UTC)

and...? Convective isolation is the key, seems like you've just proven it. :-) Vsmith 04:29, 2 Mar 2005 (UTC)

?? I just proved that convective isolation cannot possibly be the key. If convective isolation were the key, then a parked car inside a greenhouse would not get hotter than the greenhouse, because it's not "more isolated from the oustide world". The only reason it gets hotter is because it has a further radiative imbalance pushing it hotter than its ambient environment, the greenhouse. This is not powered by convection or by lack of convection. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

Thermal equilibrium and the greenhouse.

1. At thermal equilibrium the avg. thermal energy (temperature) within a container (the greenhouse) is equal to the avg. thermal energy outside.

2. At thermal equilibrium the thermal energy flow in is equal to the thermal energy flow out.

Which are you talking about?

The second one, of course. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

In a properly functioning greenhouse and in the atmosphere #1 is never achieved.
In a properly functioning greenhouse and in the atmosphere #2 exists briefly in transition twice daily. After the sun comes up and the directed radiation hits the glazing the net energy flow switches quickly from IR and conduction out > than IR and conduction in to short wavelength radiation in becomming much greater than IR & conduction out. After the sun sets the situation reverses. Thus two brief periods of energy flow in = energy flow out. But due to the brevity of the event I wouldn't call that equilibrium at all. Which of the two is your concept? No equations needed just tell me which you are referring to. Vsmith 04:29, 2 Mar 2005 (UTC)

The greenhouse can be considered in approximate thermodynamic equilibrium for most of the day, except early in the morning when the sun comes up and the temperature is rising significantly, and early at night when the temperature is dropping significantly. When the temperature is not changing significantly, as for most of the day, then it can be considered in equilibrium. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

In regards to your recently added spectroscopy reference. 90%+ irrelevant to this article. And the one relevant paragraph contains a serious misconception which renders it suspect or invalid. "The fact that water vapor, carbon dioxide, and other gases reflect infrared light is important in determining how much heat from the Earth is lost through radiation into space. This phenomenon, often called the greenhouse effect"[3] is a serious mis-statement of the concept. Why would you even include the reference? Vsmith 04:29, 2 Mar 2005 (UTC)

Uh, what do you mean this is a serious misstatement? That's precisely what the greenhouse effect IS. That page is from the analytical spectroscopy research group at UKY. The greenhouse effect is the convergence of thermodynamics (which describes systems involving temperature) and spectroscopy (which describes systems involving the interaction of light and matter), and these people do spectroscopy research (making them experts on this). I assure you that paragraph is correct. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

I can see clearly now, all those little molecular mirrors up in the sky reflecting all that IR light back to us. Must keep a herd of little elves busy polishing each molecule. :-) Vsmith 13:00, 2 Mar 2005 (UTC)

Minus the elves, that's kind of how it works. Each molecule will absorb an IR photon, which gives an electron a certain amount of energy. But that energy has to go somewhere, and it goes somewhere as an IR photon emitted in a random direction. Let's, for a simple description, consider the atmosphere as having a "bottom layer". So that bottom layer can emit the photon down, in which case it is essentially reflected back to the ground, or it can emit the photon up. But each photon emitted up has a chance of striking an atom from another layer of the atmosphere, which will reemit it in a random direction, giving it another chance to go down into the atmosphere. The average end result is that all thermal IR either escapes to space, or is reflected back down to the surface. (There is a small complication induced by the Stoke's shift of the reemitted photons, which will give a small amount of heat energy to the atmosphere, but this too will have the end result of thermal IR being emitted in a random direction, making the end result essentially equivalent to the simple form of radiation either escaping or being reflected back down.) — Cortonin | Talk 23:03, 2 Mar 2005 (UTC)

For a more intuitive level of thinking about it, you can picture what happens when you turn on the high beams of a car in thick fog, and it scatters bright light back at you. — Cortonin | Talk 23:03, 2 Mar 2005 (UTC)

This is what my elves were saying: Sometimes diagrams are drawn which show the radiation from the Earth's surface rising into the sky and being reflected off of the atmosphere (or clouds, or greenhouse gases). This too is nonsense. The radiation was not reflected, it was absorbed and different radiation was subsequently emitted. [4] Your ref. may be very good w/ spectroscopy, but the relevant paragraph is perpetuating a myth. Vsmith 01:35, 3 Mar 2005 (UTC)

Argh, I just typed a long reply to this and then I seem to have closed the browser window. That was a spectacular maneuver. In shorter form this time, your elf has some physics incorrect on that page. He says, "But, upon being absorbed, the radiation has ceased to exist by having been transformed into the kinetic and potential energy of the molecules." This is not quite correct. The only reason greenhouse gases absorb radiation is because they have an energy transition right at the energy level of thermal IR photons, for which upon absorbing such a photon, an electron moves into an excited state. The most common decay pathway for an excited electron like that is to decay into the ground state emitting a photon of approximately the same wavelength. — Cortonin | Talk 09:25, 3 Mar 2005 (UTC)

In addition, when the term "reradiate" is used, it is not used to refer to photons somehow being saved and then rereleased, but is instead simply used to refer to the energy being radiated again. — Cortonin | Talk 09:25, 3 Mar 2005 (UTC)

I'm perfectly willing to explain any of this to you that still doesn't make sense to you, but please don't engage in an edit war over this until AFTER understanding the description of the system. The goal of an encyclopedia is to inform people, not to fight over informing them. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

Ah yes, I'm just a dumb old geologist and don't know much. Just playing around a bit :-) But, I do seem to have accomplished a bit here. If you, Cortonin, will back off a bit and take a close look at what's been going on here. Your reaction here with me is exactly what you keep accusing WMC of doing. Can you see that? Now the difference, I know that WMC is an expert in his field and can respect that. However, who are you? You obviously know a bit of science, at least some jargon, - but beyond that I haven't a clue. And all them little mirrors in the sky ... Vsmith 13:00, 2 Mar 2005 (UTC)

With the slight exception of defending the spectroscopy researchers from too much ridicule, I'm not trying to make any arguments from authority here. I usually don't find them particularly useful when explanations of the phenomena are possible instead. If you knew my background you might take my description of this as true on the basis of that, but this isn't exactly the wiki way. I have gone to great lengths to try to explain the phenomenon, because I believe that if one of the editors is confused about something, then a large number of readers will be too, and so there is value in working through ways to more clearly explain this. I think we've accomplished something with all this talking, I'm simply hoping that I can explain it clearly enough to you that you can help explain the correct description of whatever it was that was confusing you at first, so that other readers aren't confused. — Cortonin | Talk 23:03, 2 Mar 2005 (UTC)

The primary difference between my approach and WMC's approach, is that my goal is not to persuade you to let me keep my version. My goal is to explain it to you (or anyone following the talk), so that you help clarify the correct description. — Cortonin | Talk 23:03, 2 Mar 2005 (UTC)

It also strikes me that you may still be confused about the directionality issue, so let me try again to explain that. From the math which describes the system, as seen below, you can of course see that directionality of radiation is not an issue. But you can also see this on an intuitive level. Consider the interaction between a tree and the ground, both inside a greenhouse. Some of the thermal IR that the ground radiates strikes the tree. And similarly, some of the thermal IR that the tree radiates strikes the ground. This can be completely neglected, however, because in equilibrium when the tree and ground are the same temperature, the radiation between the two completely balances out. And the radiation from the ground that would have gone out through the glass if not for the tree is replaced by radiation going out from the other side of the tree, so nothing is really lost here. The only thing that needs to be considered is the radiation into the system and the radiation out of the system. This is fairly standard when describing thermodynamic systems. — Cortonin | Talk 08:32, 2 Mar 2005 (UTC)

---

Maybe this whole section of the article belongs in the greenhouse article rather than here. Of course that would embroil that article in the controversy - but would be more relevant there.

-Vsmith 15:14, 27 Feb 2005 (UTC)

Well, the greenhouse page is more about the gardening applications. It would probably make more sense for the greenhouse page to link here, to the greenhouse effect (which it does). I think it's best here, first because that IS what the greenhouse effect is, and secondly because there seem to be questions about this that readers are seeking to resolve by coming to this page. — Cortonin | Talk 17:41, 27 Feb 2005 (UTC)

It seems to me it's nonetheless having a seriously distorting effect on both the structure of the page, and the resultant discussion. For all intents and purposes the two are separate in normal discourse, and the climatological sense is now the primary one. If greenhouse isn't the appropriate place for it, a separate page is always an option: greenhouse physics or greenhouse thermodynamics, or whatever. Add links all 'round. Or at least, restructure the page so that the 'real greenhouses' doesn't sound like the digression it does now, but make the two more clearly separate. At present we're getting needlessly bogged down here, essentially, on how analogous the analogy really is. Alai 07:18, 1 Mar 2005 (UTC)

Well, the climatology sense is the more common one, but the other use of the term greenhouse effect is still used quite a bit, both in gardening, and colloquially when discussing things like cars. It would be better if that section could be cast more as simply a description of how greenhouses operate when glass is involved instead of gases, rather than as a debate between two theories. I think the "bog" would be reduced if the section "convection theory" were simply removed, along with the header "thermal infrared theory", and that section were simply made the contents of "Real greenhouses", since it already includes a correct description of the role of convection. The only reason I have not fixed this is to placate WMC who will simply turn it into another edit war. If that change were made, then perhaps the description of the solar cookers and the greenhouse glazings could be merged into one slightly smaller paragraph so that it would seem like less of a digression in that portion. But I think it's important to keep a good description there of how glass greenhouses work, since apparently there is still significant confusion on this subject, and thus a description would benefit the reader. — Cortonin | Talk 07:49, 1 Mar 2005 (UTC)

For more detail, let's say F_in is the radiative energy flux in, F_out is the radiative energy flux out, F_glass is the direct heat transmission through the glass, and F_ground is the direct heat transmission through the ground. In this case, equilibrium is reached at the point where: F_in = F_out + F_glass + F_ground. (The WMC confusion comes because he's adding an F_openwindow term to the right side, completely changing the system.) F_in is a constant determined by the sun. F_out is a product of P, the fraction of thermal radiation which passes through the glass, and F_bb, the energy flux out created by the blackbody radiation in the greenhouse. F_out = P * F_bb. F_bb scales with the fourth power of the temperature, so we'll use F_bb = C * (T_g)^4, where C is a constant, and T_g is the greenhouse temperature. F_glass is determined by Newton's law of cooling, which we'll shorten to F_glass = k_glass * (T_g - T_a), where k_glass is a constant representing the rate of thermal conduction through the glass and T_a is the ambient temperature. Similarly, F_ground = k_ground * (T_g - T_a). Therefore, the equilibrium equation becomes: F_in = P*C*(T_g)^4 + (k_glass + k_ground) * (T_g - T_a). Now, k_glass and k_ground are reasonably small numbers in the insulated case, which leaves the greenhouse free to warm up to a noticeable temperature difference. In the starting condition when you "turn the sun on", T_g = T_a. There is then a radiative imbalance caused by F_in not being equal to P*C*(T_a)^4 (where in that case I use the ambient temperature, T_a). And in fact, you can see that as P gets smaller, which represents higher thermal radiation absorbance by the greenhouse glass, the P*C*(T_a)^4 is even smaller than F_in. This means that for the equilibrium equation to balance out as thermal IR absorbancy increases, T_g must grow larger, and it does. This is the mechanism by which a greenhouse actually operates. — Cortonin | Talk 10:08, 26 Feb 2005 (UTC)

(Hopefully there are no typos in the above.) Now, I'm assuming most people think the above is far too complicated to place verbatim in an article on the greenhouse effect, which is why I'm typing it here instead. Hopefully those of you who can follow the math here will understand the mechanism sufficiently from that description to work on the description in the article. — Cortonin | Talk 10:08, 26 Feb 2005 (UTC)

(And no, that is not "original research". It's a simple calculation using standard thermodynamic concepts, so please don't call it "research".) — Cortonin | Talk 10:08, 26 Feb 2005 (UTC)

In colleage days, my dorm roommate was a PhD in physics doing post doc work at school. He explained why it was often colder on a clear night than a overcast night. He described an experiment to illustrate the effect of radation out of our atmosphere. The experiment is as follows:

Some water is put in a well insulated thermo flask. The flask is put in a well insulated straight tube that is a few hundred feet tall pointing at the sky. The water is left overnight under various weather conditions.

On a clear night, the water in the flask turns into ice. On a overcast night, the water stays liquid.

The experiment set up tries to eliminate the effect of convection by using a very tall tube, eliminate the effect of conduction by using a thermo flask. The water at the bottom of this "well" is subjected to only the radiation into outter space. ON a cloudy night, the radiation is blocked, on a clear night, the radiation is freed to escape. By the Principle of conservation of energy, the setting with the escaped radiation produces ice. The other does not. You don't need to go into the nitty griddy of whether the radiation is absorbed or reflected or by elves or santa claus. The conversation of energy alone is sufficient to explain the phenomenon.

In a valid scientific experiment, interacting factors are isolated so that each effect can be studied separately. If this same experiment is done by R. W. Wood, then he will just look at a puddle of water and conclude that the wind determines the temperature of the puddle when he wouldn't bother to isolate each single factor. Kowloonese 19:45, Mar 23, 2005 (UTC)

When the discussion is going nowhere ...

I found a good article [5]. It may be worth reading before this page is getting way too long. Kowloonese 21:01, Mar 3, 2005 (UTC)

An interesting read.  :) I was going to suggest there should be a wiki page, but there already is. — Cortonin | Talk 05:20, 4 Mar 2005 (UTC)

real greenhouse move

Moved the controversial section to solar greenhouse (technical) as all that didn't really help here and was a bone of contention. Now maybe this article can avoid some unnecesary revert wars. Take the fight to the new page, the climate pages are controversial enough w/out this bit of wrangling. Vsmith 16:40, 17 Mar 2005 (UTC)

(William M. Connolley 17:12, 17 Mar 2005 (UTC)) I doubt it will help, but I suppose its worth a try.

I think this move makes the title no longer appropriate. The orginal title applies to BOTH the original physical greenhouse effect and the global warming green house effect. With this move, the original meaning is removed but the secondary meaning takes over the whole article. Ask yourself which meaning of the term "Greenhouse effect" was in use first. The physical phenomonen came first and then the meteorogists borrow the term. Now, the latter took over the former. Given the current content of this article, it should be renamed as "Global greenhouse effect". If it stays as is, then you cannot discuss greenhouse effect without mentioning the original real greenhouse. Kowloonese 00:49, Mar 18, 2005 (UTC)

Hmm... semantic quibbling. The atmospheric usage, although a probable mis-nomer, is the dominant usage as far as I am aware.

(William M. Connolley 09:34, 18 Mar 2005 (UTC)) Agree.

The article does refer to the original real greenhouse. If those who regularly edit and use this page object to the moving of the section, they are free to discuss and move it back. The prolonged debate over the actual mechanism of "real greenhouses" was distracting and seemingly of little relevance to the predominant atmospheric meaning of the current article. The technical article has also been linked to from the greenhouse page as well for those interested in how a real greenhouse works without the atmospheric connotations. Vsmith 02:34, 18 Mar 2005 (UTC)

Aside from the disagreement on whether there is a difference between the atmospheric and gardening greenhouse effect, the title is now a problem after the move. An encylopedia is not a popularity contest. You cannot drop the origin and focus on the popular aspect only. This is like writing about Muhammad Ali under the title Muhammad just because Ali was more popular to the US readers. For Ala's sake, Ali picked his name after the prophet, it is plainly wrong to drop the origin. Likewise, the term Greenhouse effect originally came from gardening, it is wrong to drop the gardening aspect from the article and move it elsewhere. One compromise is to make this page a disambig page that link to the gardening greenhouse effect and the atmospheric greenhouse effect if you insist they are different.

Contrary to WMC's opinion and the flawed Wood's paper, the two greenhouse effects are identical. The oppositing argument has missed the effect of gravity. When you factor in gravity, the effect of convection is nullified when you add enough height. For example, if you could build a greenhouse as tall as the atmosphere of the Earth, you won't see the flawed observation in the wood's experiment because convection makes no difference in such large scale greenhouse when gravity plays a part. Our Earth is a large scale greenhouse that subject to the same phyics as the garden variety. Therefore, both atmospheric and gardening greenhouse effects are the same thing, only in a small greenhouse the effect of gravity is missing and hence give you a different result. Kowloonese 20:14, Mar 18, 2005 (UTC)

Restoring the WMC text

(William M. Connolley 13:33, 7 Apr 2005 (UTC)) Per discussions with Vsmith, I've restored the GHE-is-a-misnomer section to this article. There is now a see-also to the SG(tech) page. The reasons for this should be apparent to those interested; I'll repeat them here if anyone wants to challenge this.

I've removed it again, because it's still wrong. Anyone interested in seeing why can read the discussion at Talk:Solar greenhouse (technical), where it is laid out in excruciating detail. — Cortonin | Talk 19:05, 7 Apr 2005 (UTC)

(William M. Connolley 08:55, 8 Apr 2005 (UTC)) Your own personal research is of little interest to anyone else. Its time to stop playing.

Personal research would be going back and reinterpreting Wood 1909 as still considered partially correct, as you did in your blog, and then using that to justify saying greenhouses function by convection suppression, while ignoring the rest of his conclusions. Sticking with documentation would be sticking with the description of how greenhouses function from the peer reviewed literature, in which they are described as heating over the surrounding environment due to thermal IR absorption. — Cortonin | Talk 18:40, 8 Apr 2005 (UTC)

(William M. Connolley 19:08, 8 Apr 2005 (UTC)) Now you're going totally off the rails. All the met literature, from Wood onwards, says its a misnomer: and I've supplied direct quotes to prove this. You've provided your own personal research. Give it up: you're just being silly and desperately trying to avoid losing face.

One solution to this kind of editing war is to put both views in the article. -- Kowloonese

(William M. Connolley 20:00, 8 Apr 2005 (UTC)) What a great idea! And why not put equal space for flat-earthism in the earth article while you're about it?

flat-earthism has been proven wrong. A satellite picture of the Earth ends the debate. This topic is still debatable as long as Cortonin has his point of view. But the way I am on Cortonin's side because the Wood's view does not make any sense to me. Obviously you failed to realized that Wood's view is the flat-earthism that Cortonin is trying so hard to get rid off from the article. Kowloonese 20:58, Apr 8, 2005 (UTC)

(William M. Connolley 21:27, 8 Apr 2005 (UTC)) Sure its been proved wrong. That doesn't stop the flat earth people believing it. Cortonin has been proved wrong too, and it doesn't stop him believing his stuff. Published literature trumps Cortonins personal research; sadly he has a hard time realising it.

Perhaps someone can summarize the key points on both side into a separate article and link to it. I don't trust the Talk pages because nobody monitor them and they may disappear without notice. I hope some University professors would make this topic a term paper, "Is Wood's experiment flawed and why?" I believe this is a very good teaching material for science students to critique other scientists work. If anyone look back in history of science, there were more wrongs than rights. Though the correct views will survive the test of time. If WMC goes by the number of literature he can quote, a flood of newly published rebutals to Wood's views will correct the problem. Kowloonese 19:43, Apr 8, 2005 (UTC)

(William M. Connolley 20:00, 8 Apr 2005 (UTC)) And if/when those rebuttals are published, then wiki should report them. But until they are published, Cortonins personal research doesn't supercede the met literature.

It would be a good PhD dissertation subject. One can establish a good reputation for himself by proving some age old misconcept. I am not PhD material, so I leave the challenge to others. Almost all valid theory agrees with intuition, when you read about it you will say "that makes sense". When I read about the Wood's view, the first thing came to mind is "something is missing, it does not make sense." As I pointed out in my other posts earlier, my gut feeling is that Wood failed to consider the hypothetical situation that when a greenhouse is made as big as the earth, the phenomenon is the same as in the global sense. The key point in Green House is not on how the energy is lost. It is on how the energy is captured and retained. If the Earth also has windows and the warm air trapped in our atmosphere via Greenhouse effect can be blown away by some gust of cosmic wind, then the Wood argument may be relevant, otherwise it is just BS. So the two are the same thing, it is flawed to argue that a small greenhouse doesn't work the same way. I suggest everyone read the article on antiprocess because this becomes a stalemate situation. Kowloonese 20:55, Apr 8, 2005 (UTC)

I don't care what the met literature says in passing about greenhouses. These are not greenhouse experts, and they're not describing greenhouses in any meaningful scientific detail. But if you look at all the gardening greenhouse research, you'll see exactly what I already showed you, which is that they function by thermal IR absorption. If you want to be pro-science here, then you should accept the established research describing how greenhouses operate. Pretending that I'm making it up, when I already pointed you to the literature over at Talk:Solar greenhouse (technical), is just silly. — Cortonin | Talk 20:59, 8 Apr 2005 (UTC)

(William M. Connolley 21:12, 8 Apr 2005 (UTC)) The problem indeed is that you won't accept what the met literature clearly states. By contrast, your attempts to find support from Horticern et al fail dismally, for the obvious reason that the glasshouse literature starts from the assumption that convection has been suppressed, so never considers that it might not be. As for re-starting the rv: I talked to Vsmith: he agreed with me: the compromise didn't work.

The Horticern paper explicitely includes convection into their model, as I explained on Talk:Solar greenhouse (technical), and as can be found in the paper. It follows standard practices of thermodynamics by describing energy flow in and out of the system, and these are the same standard practices we should be following on Wikipedia. Inventing other methods of analyzing the system, outside of standard thermodynamics practice, would not be productive. — Cortonin | Talk 22:26, 8 Apr 2005 (UTC)

If all your quoted literature were based on the Wood's finding, then they basically collapse into just one opinion. Kowloonese 21:27, Apr 8, 2005 (UTC)

(William M. Connolley 21:36, 8 Apr 2005 (UTC)) I don't know. You could read them and check if you like. But it wouldn't matter: wiki is here to report what the literature says, not what anyones personal physics investigations purport to demonstrate.

(William M. Connolley 21:39, 8 Apr 2005 (UTC)) To add to that: it might look from the above that I doubt the physics. I don't. I personally think the various met literature, including the Wood physics, is correct. What has proved in practice, though, is that arguing the physics with C is pointless: its like arguing evolution with a creationist, or indeed geometry with a flat earther: all references are dismissed except those he likes. So I'm now arguing from no-original-research.

For crying out loud! Buy a calculator, plug in numbers, and push buttons! Here are the equations you want, just push buttons and see the relative role of convection and radiation to the temperature of a system, greenhouse or outside. The question of how a greenhouse operates is not a thesis topic, it's an undergraduate thermodynamics homework problem, and it's being strewn out here as some grandiose debate between meteorologists and physicists/engineers. The literature describing the method of function, as exemplified by the Horticern paper, is clear and not seriously debated outside of these Talk pages. The equations describing the pathways are simple enough that anyone with a calculator can plug numbers into them and see results. Whether or not people understand the numbers they're getting, maybe that's subject to debate, but the mechanisms at work here are clear. The Horticern paper already showed the results of wind to the greenhouse system, and showed that wind sometimes increases the temperature of a greenhouse and sometimes decreases it. The reference I just pasted right here provides all the information you need to understand the role of non-wind convection, where you can see both that the magnitude of the effect of convection is small in comparison to the radiative flux, and that it is dependent on the relative temperature between air and ground, which if you've experienced much life on the planet, you will know varies both positively and negatively. Convection does not provide any systematic forcing in either direction. Thermal IR, however, does. — Cortonin | Talk 22:15, 8 Apr 2005 (UTC)

(William M. Connolley 09:08, 9 Apr 2005 (UTC)) All that is wrong. The horticern paper is *not* clear. As I said (look, we'll go round the silly loop again) the horticern paper starts by assuming that all convective loss is suppressed: therefore it tells you nothing useful about how big this term would be is it were not suppressed. The link you provide [6] doesn't help: it tells you nothing about what happens in a GH; and its for night time. Please stop wasting my time.

The Horticern paper is plenty clear if you read it carefully enough. The contributions of convection are explicitely included and described in the text, in the equations, and even in the plots. Just because it doesn't tell you the result you're looking for in the language you're looking for, does not mean it's ignoring a component. It means the result you're looking for is not supported by the physics. — Cortonin | Talk 16:18, 9 Apr 2005 (UTC)

And the link does help, because it describes the relative energy transfer the outside experiences due to convection and radiation. This is precisely what you have been arguing about, saying that the outside loses more energy due to convection than radiation. Your argument is that the greenhouse gets hotter than the outside because it loses less energy through convection than the outside, but that the greenhouse loses insignificantly less energy through radiation than the outside. The sentence can be stated equivalently in the reverse, that your argument is precisely that the outside is cooler than the greenhouse because it loses more energy through convection than the greenhouse, but that the outside loses insignificantly more radiation than the greenhouse. And if you look at the link, look at the equations, and plug in some numbers, you'll see that this is wrong. You don't have to consider the sun in order to see the relative behaviors of convection and radiation, you only have to consider convection and radiation. — Cortonin | Talk 16:18, 9 Apr 2005 (UTC)

Lindzen quote

Removed the following:

For a theoretical case if no other greenhouse gases were in the atmosphere, Richard Lindzen estimated 98% (Global warming: the origin and nature of the alleged scientific consensus. Regulation, Spring 1992 issue, 87-98 [7]).

as it is an unsupported quote from a Business & Govt publication. Seems rather an irrelevant statement. -Vsmith 16:24, 10 Apr 2005 (UTC)

For the estimate of what percentage greenhouse effect would remain if carbon dioxide were removed, I've seen numbers of 85%, 88%, 90%, 94%, 95%, and 98%. For the 98%, I think Lindzen may include atmospheric convection feedbacks, but I'm not sure. Is the 98% an extremum? Yeah, definitely. It's on the edge of the numbers I've seen, in the list there. 5.8 degrees of predicted warming is also an extremum outside of the mainstream calculations, but we include that too. The NPOV policy instructs us to include prominent information that can be attributed to prominent groups or individuals, and this certainly qualifies. — Cortonin | Talk 18:56, 10 Apr 2005 (UTC)

I modified the tone slightly, since it's not clear precisely how he calculates this number, and I presented the atmospheric convection feedback alluded to by the surrounding text in the reference. It is a frequently quoted number, so its absence will only warrant its inclusion later. — Cortonin | Talk 19:31, 10 Apr 2005 (UTC)

To obtain this estimate, he may have included various theorized atmospheric feedbacks. and he may have just pulled it out of his hat - seems a bit odd to add our interpretations or suppositions (isn't that akin to orig. research?). I don't think the NPOV policy means that we must include all prominent info no matter how questionable or irrelevant. To me this extremum is both questionable and irrelevant as we don't have direct info on how the number was derived or imagined. Therefore, I say begone with the meaningless tidbit. Vsmith 02:56, 11 Apr 2005 (UTC)

(William M. Connolley 08:59, 11 Apr 2005 (UTC)) I too say begone with it. For one thing, For a theoretical case if no other greenhouse gases were in the atmosphere is my words, not his - and I realised they were wrong. If anyone wants the 98% value in, it needs to be (a) properly sourced (to science, not Cato) (b) correctly described.

Here is a little more reading. [8] (SEWilco 20:29, 11 Apr 2005 (UTC))

• "4. CO2 contribution to the ~33°C natural greenhouse effect
  • Lindzen: "Even if all other greenhouse gases (such as carbon dioxide and methane) were to disappear, we would still be left with over 98 percent of the current greenhouse effect." Cato Review, Spring issue, 87-98, 1992; "If all CO2 were removed from the atmosphere, water vapor and clouds would still provide almost all of the present greenhouse effect." Res. Explor. 9, 191-200, 1993.
  • Lacis and Hansen: removing CO2, with water vapor kept fixed, would cool the Earth 5-10°C; removing CO2 and trace gases with water vapor allowed to respond would remove most of the natural greenhouse effect."

(William M. Connolley 21:17, 11 Apr 2005 (UTC)) Thanks. OK, so for Lindzen, thats the same non-sourced thing again (Cato), except it is clear now that he includes clouds rather than just GHGs (Res Explr, whatever that is: who is the author?). So its now quite clear that asserting that WV causes 98% of the GHE is wrong, even from Lindzens numbers. But we don't know what Res Explor actually said or who wrote it.

My revert

I don't endorse the way WMC and Cortonin are gaming the system. One reverts 4 times in 23.8 hours, the other reverts 4 times in 26 hours. The 3RR is not a game, it's not a right - it's a limit on bad behaviour. I don't think that 26 hours is any better than 24. They can both return to their revert war tomorrow. Guettarda 20:24, 14 Apr 2005 (UTC)

Maybe you could try editing by the content rather than editing by the people. Let's not lose sight of what the goal of this whole project is supposed to be. — Cortonin | Talk 22:33, 14 Apr 2005 (UTC)

True, that would be preferable. Can you find someone who supports your interpretation of the physics here, someone who can argue the case without the baggage that you (and William, in fairness) bring to this issue? Guettarda 00:01, 15 Apr 2005 (UTC)

That comment is still editing by the people. These are simple issues which can be edited without all the interpersonal melodrama and taking of sides. It's not even an environmentalist issue, and has nothing to do with advocacy or opposition to any environmentalist position, but still all the environmentalists who edit here are clumping together, perhaps out of habit. This is simply about describing the physical mechanism for how a gardening greenhouse works. If you want to understand the mechanism in detail, read Joliet O, et al., Agricultural and Forest Meteorology 55(3-4): 265-294 Jun 1991. — Cortonin | Talk 00:28, 15 Apr 2005 (UTC)

(William M. Connolley 21:56, 15 Apr 2005 (UTC)) If you can find it easily, then I recommend reading the Joliet paper, if only to discover that it doesn't have anything germane to say. But if its hard for you to find, then don't bother.

I already explained to you on Talk:Solar greenhouse (technical)#Atmospheric Convection why your belief that it is unrelated is incorrect and based on a significant misreading of the paper. It in fact, directly addresses and describes the full mechanism. That its description is complete is confirmed by its strong predictive correspondence to experiment for various greenhouse types and conditions. Anything additional is a small minor effect, or not confirmed by experiment. — Cortonin | Talk 22:18, 15 Apr 2005 (UTC)

Atmospheric convection

Vsmith, I appreciate you taking the time to consider the merits of the individual aspects of part of the edit. I am removing the portion that says "within the atmosphere", because that seems to be implying some sort of horizontal convective flow changing the average temperature. Horizontal convective flow would only minorly affect the average temperature, but since thermal IR scales with the fourth power, horizontal convective flow could actually decrease radiative loss and thus increase average temperature. For example, [(280^4-260^4)+(270^4-260^4)]/2 > 275^4-260^4. — Cortonin | Talk 18:16, 23 Apr 2005 (UTC)

At first I thought the "within the atmosphere" was rather redundant and obvious, but the wording "through the thermal IR absorbence of the atmosphere" seemed to imply out of the atmosphere although I assumed that was not the intent. As to horizontal convective flow, that is a most important part of the convective heat energy redistribution within the atmosphere even though it may have only a minor effect on the global energy balance total. Hadn't considered the horizontal component as a significant factor in decreasing radiative loss, more to think about :-) Vsmith 23:10, 23 Apr 2005 (UTC)

Right, it's an important part of the redistribution, but in general, horizontal convection's contribution to the average temperature should be a slight increase. (It should be possible to construct an area where horizontal convection would decrease the the average temperature of that area, if the right surface materials were chosen, but on average, the result should be an increase to the average temperature for the reason given above.) I saw what you were doing with the "partly above" to imply not leaving, and this is a good patch. — Cortonin | Talk 02:54, 24 Apr 2005 (UTC)

The great revert war

(William M. Connolley 19:31, 30 Apr 2005 (UTC)) Judging from his recent edit comment Published literature not "simplistic", "other" more neutral, and opening a window tells no more about greenhouse operation than opening an oven door. (Maybe try to think of reasons for your rv?) Cortonin seems to have forgotten what this is all about. To refresh the memories:

The published met literature clearly shows that the GHE is a misnomer, since its not the mechanism that heats greenhouses. This is clearly referenced in my version. Cortonin, on the basis of his own personal research and animosity towards me, cannot accept this explanation, so proposes his own, unsupported by any published reseach. And its as simple as that.

An interesting interpretation. You have shown a paper from 1909 which attempts to prove that there is no infrared greenhouse effect and thus no atmospheric greenhouse effect. Science has progressed quite a bit since then, and we now know this to essentially be crap and based on a faulty experimental design.

(William M. Connolley 20:05, 1 May 2005 (UTC)) Sigh. I have cited a large number of pieces from the met literature, most of which you've never bothered to read. The design of the original experiment remains as valid as ever, yuor categorising it as "crap" tells us more about your mind that the met literature; your assertion that all the met literature relies on this oe expt remains as invalid as ever.

It is not a controlled experiment because there is no control. There are two variables, and they are compared. In the beginning result, he hits temperatures of 65C. Then he reaches temperatures of 55C by putting another glass plate up (where an additional glass plate should not properly cause that much drop in heating, since most of the solar energy should pass through glass), but the worst part is that he puts it over both systems, leaving both systems having variables. One has two glass plates with an unspecified distance between them, and the other has a glass plate and a rock salt plate, with an unspecified distance and air flow between them. Two variables, no control. This is fairly meaningless for drawing the conclusion he does, which is why his conclusion that there is no atmospheric greenhouse effect is wrong. This is basic scientific method that he's failing to consider, and if he tried to publish such an experiment today, he would be literally laughed at. — Cortonin | Talk 21:33, 1 May 2005 (UTC)

(William M. Connolley 21:19, 2 May 2005 (UTC)) You think his conclusion is wrong, but why should we care about your opinion? You are anonymous. You provide something that rejects Wood - fine. But you don't. There is nothing that superceedes Wood, for the obvious reason. All your reasonning... is just your reasonning. Its of no interest to the wide world. Stop pushing it.

Nothing supersedes Wood?? Then I guess we can all go home and stop editing the Greenhouse effect page, since Wood clearly stated, The heat received is thus stored up in the atmosphere, remaining there on account of the very low radiating power of a gas. It seems to me very doubtful if the atmosphere is warmed to any great extent by absorbing the radiation from the ground, even under the most favourable conditions. So if nothing supersedes Wood, then obviously there's no greenhouse effect. The clearest part of Wood's paper was his concluding paragraph which stated, I do not pretent to have gone very deeply into the matter, which is quite true. Did he stop to consider the absorption nonlinearity of putting two glass plates in a row? No, in fact he assumes they are linear which they are not. Did he stop to consider that rock salt has three times the thermal conductivity of glass? It would appear not. Could we perhaps stick to a little more quality from the peer reviewed literature, since it exists, rather than "communicated by the author" publications from 1909 which are self-professed to be particularly non-thorough? — Cortonin | Talk 06:29, 3 May 2005 (UTC)

The prominent supporters of this paper seem to be you, and the guy at the website "Bad Meteorology". In contrast, all of the greenhouse engineering articles in the literature, and standard greenhouse practices note that solar-heated greenhouses heat over their surroundings by means of having a glazing surface (such as glass) which permits solar input but blocks thermal exchange with the significantly cooler upper sky.

(William M. Connolley 20:05, 1 May 2005 (UTC)) All the GH eng literature starts off with the unstated assumption that all convection is suppressed. Hence, of course, there is no attempt to assess the relative roles of convection and IR, since convection is known to be zero.

That is incorrect. The agricultural engineering literature does NOT assume that all convection is suppressed, and does not leave it unstated. It instead, assumes convection is non-zero, and includes its contribution directly, including its functional dependence on windspeed. You ignored me all the other times I explained this to you. — Cortonin | Talk 21:33, 1 May 2005 (UTC)

(William M. Connolley 21:19, 2 May 2005 (UTC)) Sigh. You are still wrong. Convection, from within, is zero/suppressed, of course, since there is a physical barrier in the way, as I've previously explained all too often. You are confusing this with the heat flux from the top of the roof, which is entirely different.

Apparently you searched the paper for the word "convection".

(William M. Connolley 19:29, 3 May 2005 (UTC)) No.

Now try it again, and this time either try actually reading the paper,

(William M. Connolley 19:29, 3 May 2005 (UTC)) Please be less condescending, or your comments won't be read.

or search for the word "infiltration", and you will see that it is explicitely included for a range of non-zero values, calculated within the model, and experimentally confirmed to be correct. — Cortonin | Talk 01:09, 3 May 2005 (UTC)

(William M. Connolley 19:29, 3 May 2005 (UTC)) there is a physical barrier in a GH. This affects the physics.

Yes it does, and that physical barrier is modelled completely in the Horticern paper. They include air infiltration through the physical barrier, for sealed barriers and for barriers with a range of open holes, and even include the wind dependence by which infiltration increases with wind. They also plot this and test this. — Cortonin | Talk 20:56, 3 May 2005 (UTC)

However, you've latched on to this "misnomer" word, and as a result, keep trying to say that's all wrong with some ambiguous

(William M. Connolley 20:05, 1 May 2005 (UTC)) Since I've cited a large number of very specific references, your use of "ambiguous" is quite unreasonable.

Show me a peer reviewed paper which focuses on describing the mechanism of a greenhouse, and which supports your point. Because I already showed you one which rejects it. — Cortonin | Talk 21:33, 1 May 2005 (UTC)

(William M. Connolley 21:19, 2 May 2005 (UTC)) I've shown you papers and books which explicitly call the GHE a misnomer - you ignore them all. By contrast, you cite irrelevant papers, which do not even address the question.

Name one peer reviewed paper you've put forth which presents a model in which the GH does not operate by thermal infrared absorption and verifies this experimentally. — Cortonin | Talk 01:09, 3 May 2005 (UTC)

(William M. Connolley 19:29, 3 May 2005 (UTC)) The Wood paper, of course.

First, the text is labelled "Communicated by the Author". Second, prior to the 50's, peer review was sporadic at best, and only even then in some journals. In that time period, people did not have to show their ideas correct to get them published, but instead others had to show them wrong. And if they had previously published in a specific journal, articles were typically just waved through. As a result, more crap was published, and thus the system was changed to what we have now. So it's highly unlikely that the Wood paper was at all peer reviewed. Care to name one that actually was? (Hint, maybe you could look at the Horticern paper.) — Cortonin | Talk 20:56, 3 May 2005 (UTC)

reference to "met literature", even though the gardening greenhouse is not a meteorological topic, but an engineering, spectroscopic, and thermodynamic one. — Cortonin | Talk 20:18, 30 Apr 2005 (UTC)

No one is disputing the meteorological literature in that there exists a global thermal infrared greenhouse (well, no one except the Wood 1909 paper you keep inserting). The only question is whether or not this article will correspond to the agricultural engineering literature which describes gardening greenhouse function. — Cortonin | Talk 20:18, 30 Apr 2005 (UTC)

Even if I get hit by a bus tomorrow, this debate isn't going to end. You have written, The warming inside a greenhouse thus occurs by suppressing convection and turbulent mixing. This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature will drop considerably. Everytime a physicist stumbles across this page, the reverting will resume, because that is dicrectly contrary to standard reasoning in thermodynamics. You are somehow implying that the effects of establishing thermal contact with a reservoir directly implies something about the lack of thermal contact with the reservoir. It's the logical equivalent of saying that the refridgerator is cold because there is no toaster oven running inside of it. We spend countless hours drumming exactly those types of misconceptions out of the heads of undergraduates in thermodynamics classes. — Cortonin | Talk 20:37, 30 Apr 2005 (UTC)

(William M. Connolley 20:05, 1 May 2005 (UTC)) You're still pushing your pet theory, which is contrary to the principles of wiki.

The "pet theory" is that opening a window tells you how the greenhouse operates. I will reemphasize: Bringing two systems into thermal contact makes the temperatures equalize. Taking two systems out of thermal contact does not make them unequal, it simply permits another forcing agent to make them unequal. These are some of the most basic principles of thermodynamics, and are literally as "original research" as Newton's laws. — Cortonin | Talk 21:33, 1 May 2005 (UTC)

(William M. Connolley 21:19, 2 May 2005 (UTC)) Which is just what everyone pushing original research says: "its obvious really" they all say, but the point is to provide relevant refs, not irrelevant ones and your own work.

What is more complete than a complete mechanistic description of the function of the greenhouse including all the energy flow in and out??? This is what I have provided, and you just ignore it, call it irrelevant, and keep leaning on a 1909 essay. If a paper models the complete mechanism for greenhouse function, including all energy flow in and out, and compares this result to experiment and the model results in a correct prediction of the experimental results, then the model is, to the extent of known science, correct! This is the basis of the scientific method. To postulate that there are other effects which dominate, when the model provided correctly matches experiment, makes no sense. If the Horticern model ignored dominant effects, its predictions would NOT match experiment, but, as described, it does. — Cortonin | Talk 01:09, 3 May 2005 (UTC)

(William M. Connolley 19:29, 3 May 2005 (UTC)) What you are still failing ot understand is that the GH eng literature assumes the presence of a physical barrier, so all its calcs are done on the basis of that barrier being present, ie convection being suppressed. Convection starting from above the barrier is a totally different matter.

No, the GH eng literature specifically addresses convection past the barrier, and the term used is sometimes "convection" and sometimes "infiltration". The calculations are made explicitly, and are successfully compared to experiment. — Cortonin | Talk 20:56, 3 May 2005 (UTC)

Envision a sheet or roof of glazing material say 2 m X 3 m in area, position it 2 m above the ground and parallel to the ground. Leave this "greenhouse" open on all sides. Conduct your experiment on a windless day for say 24 hours. How effective is this simple open "greenhouse"? Is my little "thought experiment" silly?
Now why do all of the glazing research papers (the ones I've seen) start with the assumption of a convectively closed system? Because without that convectively closed system prerequisite their glazing research is essentially meaningless. The most basic requirement for any effective greenhouse is convection blockage. It is so basic that all greenhouse design research starts with that as a given. And of course all of Cortonin's thermodynamics is quite valid for a convectively closed system. Now if you can provide research based on my convectively open flat-roofed open-sided greenhouse system, I would be most interested. :-)
It seems to me that this great revert war could be ended if the warriors weren't arguing from positions 90 degrees apart. Will my little thought experiment solve the problem? Hmm...... -Vsmith 02:27, 3 May 2005 (UTC)

Well, I don't expect you'll find a paper in the literature titled "temperature under a big glass plate". But the next closest thing I found is a detailed analysis of a more useful device, a forced convection greenhouse drier. A nice description can be found in "The performance of forced convection greenhouse driers", Condori M, Saravia L, Renewable Energy 13 (4): 453-469 Apr 1998. Basically, it's a greenhouse with a huge fan forcing air in from the environment and back out to the environment. And these greenhouses, despite having large amounts of forced convection, still achieve hot temperatures (for example, 50C). So yes, fairly significant heating DOES still occur due to the thermal IR absorption even when there is a large amount of convection (for example, 400L/s). — Cortonin | Talk 06:15, 3 May 2005 (UTC)

And like I said above, this is explicitely included and accounted for by the Horticern model, and the results tested. — Cortonin | Talk 06:15, 3 May 2005 (UTC)

Isn't a greenhouse dryer simply using the reduced relative humidity due to the temperature rise? The sunlight would be hitting the material to be dried if it were outside, but inside the greenhouse the environment is more controlled than out in the open. The "big fan" is to force out humid air so some fresh air can enter, be heated, and be a drying agent. The big fan only proves that fresh air is needed (and I avoided here saying why the temperature rises). (SEWilco 17:26, 3 May 2005 (UTC))

The point was that the temperature still rises significantly even in the presence of forced convection. Convection of cooler air through a greenhouse will obviously cool it a bit, but the point is that the lack of convection is not what causes it to rise, because even when convection is present or even forced, the temperature still rises significantly. — Cortonin | Talk 20:56, 3 May 2005 (UTC)

Differences in scale

Perhaps someone can clarify in what way a garden greenhouse is different from the global greenhouse? There seems to be disagreement about whether a single factor is overwhelmingly dominant. Firstly, can you identify the differences? Secondly, why does it matter? Can we just say "The analogy is flawed by oversimplification and the differences are:…" ? (SEWilco 05:23, 3 May 2005 (UTC))

• Radiation blockage (depending upon materials):
  • Garden greenhouse blocks escape of some radiation.
  • Global greenhouse blocks escape of some radiation.
• Convection:
  • Garden greenhouse has warm air which can only circulate through convection within the greenhouse.
  • Global greenhouse has warm air which can only circulate through convection within the atmosphere.
• Heat storage:
  • Garden greenhouse kept warm at night by warm contents and ground.
  • Global greenhouse kept warm at night by warm surface.

I just read most of the discussion this morning. IMHO the difference is that the reflection of IR radiation plays a major role in the (global) greenhouse effect, while it plays a much smaller role in the garden greenhouse (where the prevention of convection is the dominating contribution).

(William M. Connolley 19:22, 3 May 2005 (UTC)) Ah, well done, yes, this is exactly my position.

The "open a window" example is not very convincing to me and I would indeed remove that part from the article.

(William M. Connolley 18:18, 5 May 2005 (UTC)) ? The open a window bit is indeed convincing. Opening a small window has a far larger effect than you would expect from the radiative POV.

You're confusing cause and effect. Opening a window only has a significant effect because the greenhouse is already far above the ambient temperature due to thermal IR absorption. You say you're a mathematician by training, so perhaps somewhere along the line you ran into the difference between the inverse and the contrapositive. The inverse does not logically follow from the original statement, and you're trying to use argument by inverse as a proof method here with the window opening line. It's just faulty logic, from basic logic theory. You're saying "opening a window lowers temperature" implies "closing a window raises temperature", which is argument by inverse, and is incorrect logic. The correct statement is the contrapositive, such that "opening a window lowers temperature" implies "higher temperature means the window is closed". That's all. It doesn't yield ANY information about how the higher temperature is obtained, because there is no causal connection in the reverse direction. This is not "perspective" or "point of view", it's basic logical reasoning. — Cortonin | Talk 21:03, 5 May 2005 (UTC)

On the other hand I have seen no counter argument to the experiment of Woods that an opaque (wrt IR radiation) window leads qualitatively to the same effect (an additional reflection term of course will lead to even higher temperatures). --mkrohn 09:57, 3 May 2005 (UTC)

For a qualitative (and quantitative) comparison of the contributions of convection and radiation in the literature read Joliet O., et al.; Horticern - An Improved Static Model for Predicting the Energy-Consumption of a Greenhouse, Agricultural and Forest Meteorology 55(3-4): 265-294 Jun 1991, A detailed explanation of the gardening greenhouse mechanism. Also, there is significantly more discussion at Talk:Solar greenhouse (technical) about the mechanism of gardening greenhouse operation. — Cortonin | Talk 10:31, 3 May 2005 (UTC)

(William M. Connolley 19:22, 3 May 2005 (UTC)) The horticern paper is irrelevant, because it begins by assuming a material barrier, ie suppression of convection.

For credibility's sake, you really should check the paper again more carefully before you keep repeating that. — Cortonin | Talk 21:21, 3 May 2005 (UTC)

(William M. Connolley 18:31, 4 May 2005 (UTC)) Oh good grief, read the thing yourself. It assumes suppression of convection from inside to outside, of course, because there is a barrier in the way - the roof. Have you really failed to understand that? The turbulent heat terms from the top of the roof are a different matter entirely.

Perhaps I "failed to understand" what you think it says because I read the whole thing, and noticed the section conspicuously labelled "exchange between inside and outside air", the accompanying equations, the graph which it is stated includes air infiltration between the inside and outside, and the total of fourteen references to air infiltration between the inside and outside sprinkled throughout the article. — Cortonin | Talk 06:31, 5 May 2005 (UTC)

(William M. Connolley 18:18, 5 May 2005 (UTC)) Air infiltration is indeed a large term, why should surprise you, since the GH is close to sealed. This reveals how large a role convection would play, were it allowed to.

Hypothesizing contributions which are not measured and not required by the model, but which you think would be there if they were allowed to does not make sense. See Occam's Razor. — Cortonin | Talk 21:03, 5 May 2005 (UTC)

Cortonin, you have just answered any questions I had re: the Hortichem paper that I don't have access to. It is obvious from your comment above that, like all glazing researchers, they start from an isolated system and do not consider real convection. Occam's razor does not apply when you are dismissing factors that haven't been tested and simply ignored by the model or defined away. The major factor is blocking of convection, And all of your references and thermodynamic equations simply ignore that and start from the given that convection is blocked. You have totally convinced me and removed any doubt I had, thanks. -Vsmith 23:21, 5 May 2005 (UTC)

I think you completely misunderstood what I typed. I said "contributions which are not measured" meaning "contributions which are not observed," not "contributions which are not looked for." The Horticern paper DOES EXPLICITELY include convection from the inside air to the outside air in their model, and does explicitely make measurements which include the contributions from this convection. Convection HAS been tested, HAS been incldued in the model, and has NOT been defined away. I don't think I can say it any clearer. Please don't make any assumptions that are opposite to this unless you have read the paper yourself, because I assure you it is explicitely included, and I have pointed out precisely where in the paper. — Cortonin | Talk 04:51, 6 May 2005 (UTC)

The IR argument is tested at night, when the Sun is no longer applying heat and losses are the significant factor. When there are no clouds, temperature plummets at night on the surface; is IR being absorbed higher in the atmosphere or being lost? (See present day/night springtime Wisconsin temperatures, see IR weather photos) And for those claiming glass blocks IR: do you have a solid state camera or TV camera? Or a camera phone with "night" setting? Try looking at heat sources (stove, oven, aquarium heater, space heater, people) through ordinary glass. Try looking at a nearby greenhouse at night (look under "Flowers" in Yellow Pages). (SEWilco 17:40, 3 May 2005 (UTC))

(William M. Connolley 19:22, 3 May 2005 (UTC)) But we're talking about daytime, not nighttime.

Actually, we're talking about both. Both global and gardening greenhouses spend 50% of their time during the night. — Cortonin | Talk 21:21, 3 May 2005 (UTC)

SEWilco, you are right that the nighttime provides the most clear test of thermal IR. As far as the equations are concerned, day and night are exactly the same, except that day has an input flux of solar energy. But both day and night experience the same equations for thermal loss by convection, conduction, infiltration, and radiation to the sky. For understanding the significance of the radiative contribution, it's important to keep in mind that the radiative sky temperature is on average somewhere around 16C cooler than the ambient temperature, so radiative exchange with the sky is like keeping an ice pack on your head. This is precisely why the temperature drops so quickly on a clear night. A greenhouse, however, does not experience this drop, even though the environment right outside of it does (and the same heat loss happens continually throughout the day too). — Cortonin | Talk 21:21, 3 May 2005 (UTC)

And regarding the IR cameras, that won't work. Those cameras view NIR (near-IR), and not thermal IR. Check infrared for a description of the subbands of IR, and check Wien's displacement law for a description of how to calculate the wavelength of thermal radiation at a specific temperature. (Room temperature is about 10µm). — Cortonin | Talk 21:21, 3 May 2005 (UTC)

Greenhouse

I just talked with two PhDs from the meteorology department and they both agree that literature says that the dominant effect in greenhouses is the prevention of convection. But before I start editing anything I will hopefully have the opportunity to consult some more literature (as time permits) :-). -- mkrohn 17:18, 4 May 2005 (UTC)

I talked to some coworkers from the physics department where I am, and they said, "No, it's radiation." They also didn't understand why this was even being debated. — Cortonin | Talk 06:24, 5 May 2005 (UTC)

P.S. @Cortonin: From what I understand you showed us (in the calculation above) that in the equilibrium (of radiation) the temperature in the greenhouse is higher than outside (assuming we have reflection from the glas). This is of course trivial and I think nobody seriously disputes this. On the other hand I fail to see where the convection in your considerations is. To be more precise: without a greenhouse you get permanent cooling from above because the hot air rises and colder air comes down to the bottom.

Well, first, it IS being disputed by the WMC edit. His edit keeps saying that greenhouses warm by convection suppression, and that only the global greenhouse effect experiences a radiative contribution. (Thus, the continued reverting because what you say "is of course trivial" is being replaced by that.) — Cortonin | Talk 06:24, 5 May 2005 (UTC)

As for convection, its contribution is being significantly overstated. First, you are postulating some large source of cool air above us. But in reality, the cool air is pretty far away, and the thermal interchange due to convection at such large distances is pretty slow. If you stand on top of a 20 story building, it's not really much colder than on the ground (maybe on average half a degree lower). It's may feel a bit windier up on top of a building, but the actual temperatures are insignificantly different. Here's a graph of temperature versus altitude as an example ([9] or [10]). In addition, there is no permanent cooling from convection. In fact, convection often warms the ground, and on average spends about half of the time doing so, in particular when a warm front moves in, and most of the night and in the morning. See this homework problem for short discussion. Perhaps the meteorologists you asked were getting confused by thinking in terms of kilometers, but we're not dealing with many-kilometer high greenhouses, and convection over the range of kilometers is a very slow process in comparison to radiative exchange. — Cortonin | Talk 06:24, 5 May 2005 (UTC)

Personal observation here. I live in a narrow Ozark valley with ridges some 100 to 150 feet above the narrow valley floor. On a clear still night the temperature in my valley is 5 - 10 degrees C colder than up on the ridges due to convective flow, you can feel the cool breeze flowing down the valley. Really noticeable in winter Brr... It's called a frost hollow for a reason - and it dramatically illustrates the reality of near surface convection. Vsmith 03:55, 10 May 2005 (UTC)

Actually, what that's illustrating is that on a clear still night, the temperature drops due to radiative exchange with the night sky (which would be shielded more significantly, by about a factor of 2.5, on a cloudy night). This is why the temperature is coldest near the ground, because the ground is what takes part in the radiative exchange. The air a little bit higher above the ground stays warm from the heat it gained throughout the day. If the convection were as significant as is being proposed here, this would not happen, because the cold near the ground which is brought about by radiative exchange would be rapidly warmed by convection with the warmer upper air (which you can feel by going up the mountain, as you mentioned). — Cortonin | Talk 05:04, 10 May 2005 (UTC)

No. Actually it is illustrating convection in a microenvironment, that convective flow is critical to the microenvironment, and it's the reason I don't have a peach orchard in my valley. A bubble of air that is warmer than its surroundings will convect away, so a greenhouse is built around that warm bubble to stop that convection and retain the heated air. Once the bubble is trapped then we can start worrying about better glazing and insulation to keep the bubble warmer longer. It is really quite that simple. Vsmith 15:19, 10 May 2005 (UTC)

The same effect occurs in the midwest, where the surface temperatures drop way below the higher air on a calm clear night, and there isn't a mountain or wall to be found for quite some distance in much of the midwest. So it's a radiative effect. The only difference in the midwest is that there are no mountains to climb to check that the temperature is warmer up there, but if you send a balloon up you can confirm it. — Cortonin | Talk 16:51, 10 May 2005 (UTC)

The meterologists I asked perfectly understood what I wanted. Initially I asked them about how a greenhouse works and what the dominant contributions are. They mentioned both: convection and reflection and said that the convection is probably the dominant part. Then they did go on (without me mentioning the global greenhouse effect) that there is a difference between the greenhouse and the (global) greenhouse effect, namely that convection is surpressed in the greenhouse. Though they admitted that this knowledge stems from standard textbooks and they never did any calculations on their own.

Cortonin, just to get this right: what is your prediction for a greenhouse (with non-reflecting glas). From your arguments I conclude that you predict that almost no heating will happen, right? -- mkrohn 00:40, 6 May 2005 (UTC)

A greenhouse constructed out of a completely transparent glazing over the complete range of UV through thermal IR would, on average, result in some warming in comparison to the surrounding environment during mid-day into evening, but way less heating than a greenhouse with a thermal IR absorbent glazing. But this same greenhouse would then on average result in COOLING compared to the surrounding environment during the night and into the early morning. During the night, the outside environment is kept warm by the air above it while the ground cools off rapidly by radiative exchange with the night sky. A greenhouse which is cut off from this warmth from the air, but still in radiative exchange with the night sky, would be cooler than the surrounding environment at night by about the same amount that it is warmed during the day into evening. The magnitude of the fluctuation in temperature for such a design would be much smaller than the heating resulting from a greenhouse with a thermal IR absorbent glazing, and because half of the time it is below the outside temperature, the average temperature inside the greenhouse throughout a 24 hour period is much much closer to the ambient average. This is perhaps why WMC does not wish to discuss the nighttime component, because the reasoning on the convection model reverses during the night. The effects of thermal IR absorption, in comparison, remain strong and in the same direction at all times (although with the largest contribution on clear days and nights, when the surrounding environment loses heat to the sky most rapidly). — Cortonin | Talk 05:17, 6 May 2005 (UTC)

Horticern paper

I have done a preliminary read of the Horticern paper by Jolliet et. al. (Agricultural and Forest Meteorology, 55, 1991, 265-294). Thanks Cortonin. It is a very detailed report of investigations of greenhouse efficiency and a computer model. The research was done on a large commercial working greenhouse. The greenhouse environment was of course enclosed. The bulk of the report is not really applicable here. Again I have not fully digested the whole thing, but one quote seems to be immediately of interest here.

"The energy loss due to air renewal by infiltration represents about 20% of total losses and depends on the quality of the joints, cladding area, windspeed and inside-outside temperature difference." p.274.

If within a closed greenhouse environment some 20% of energy loss is due to infiltration or convection through leaks and unsealed joints, that speaks volumes about the importance of convection blocking to the maintaining of the heat from captured solar energy.

Bear in mind that this is describing energy loss, not energy not-lossed. Part of the big problem here, is that people are trying to describe the greenhouse in a language of not-exchanged energy, which is a fictional concept not present in thermodynamics, and is resulting in much confusion. Thermodynamic systems must always be described in terms of what IS happening. — Cortonin | Talk 05:31, 10 May 2005 (UTC)

What 'is happening is that a bubble of warm air, which is out of equilibrium with its surroundings, will convect away. The first and most basic function of a greenhouse is to enclose that warm bubble so it doesn't immediately convect away and the heated air is held within the volume of the greenhouse. Once that convection-blocking step occurrs then we can worry about better glazing and insulating materials to keep the heat trapped longer. And this is where all of your glazing research papers come in to play - after the bubble is trapped. As to "what IS happening", what is happening is that the bubble of air is first isolated and then the glazing people go to work to improve the energy retention within the trapped bubble. But, first you have to trap it :-) Vsmith 15:52, 10 May 2005 (UTC)

Let's go back to your little valley for a moment. Take your little valley at night, where the surface temperatures are cool, and the air above that it is warmer. In this situation, increased convection is increasing the temperature of the surface. Similarly, if you put a greenhouse in that valley without considering radiative blocking, that greenhouse will become cool just like its environment, and the convection with the air above will be actively attempting to warm the greenhouse. Blocking that convection then by a wall around the greenhouse will only stop that warming, making the inside of the greenhouse slightly cooler than the outside environment which receives that additional warming from the air above, right? Have you considered this? "Convection suppression" does not always warm. — Cortonin | Talk 17:16, 10 May 2005 (UTC)

Excuse me - "Convection suppression" does not always warm. In my view convection suppression essentially never warms, and neither does the glazing. The heat comes from the incoming solar energy. A greenhouse simply acts to hold onto that heat a bit longer, mainly by blocking convection and then to a perhaps lesser extent by absorbing or blocking outgoing IR. Your analysis of valley convection is absurd - warm air above does not sink into the valley and displace the cold surface air - density diffs. drive convection and warm low density air doesn't sink and push cold dense air up. Vsmith 20:30, 10 May 2005 (UTC)

Another quote: "It clearly indicates that for an air-tight greenhouse, the influence of sky temperature is much higher than that of windspeed." p.277. Emphasis added to point out that this study as other greenhouse glazing research begins with the given that convective exchange is blocked and not considered in the model beyond the leaks referred to above. The appendix does provide a factor for air infiltration up to .002sq.m./sq.m of glazing for leaky cover with cracks or holes, but I haven't plugged the numbers in to the given equations, perhaps I should plug in a factor of 1 for an open greenhouse.

The glazing does not independently produce heating, but it does actively block a constant cooling. The radiative sky temperature is on average around 16C below the temperature of the outside surface environment (about 26C below on clear days and about 6C on cloudy days). By comparison, the air being exchanged by convection is very close to the same temeparture as the surface temperature, sometimes less, sometimes more (although yes, convective flow is higher when the surface air is warmer than when temperature inversion occurs). Now, let's consider a simple little situation right after the sun goes down, and let's say we have a greenhouse starting out at this time at the same temperature as the outside environment. By the "convection suppression" theory, the temperature should stay about the same as the outside, since there is no sunlight coming in, and there is very little convection outside because the air above the ground is actually hotter, reducing convection (although we have no idea why it's hotter under the "convection suppression" theory). By the thermal IR glazing theory, the temperature inside the greenhouse will be hotter than the outside by the end of the night. The greenhouse won't get any hotter than it was when it started, but the outside environment WILL cool off substantially by radiative exchange with the upper sky, which is significantly cooler than the surrounding environment. — Cortonin | Talk 03:36, 11 May 2005 (UTC)

Now, in reality, the second one is what actually happens. The greenhouse maintains its temperature, and the outside environment cools off. So if you want to know why a greenhouse is hotter, you have to examine why the outside environment loses its energy when the greenhouse does not. So let's try to examine this in terms of convection: The outside world shouldn't lose energy like that. We know that for a distance the temperature gets hotter at night as you move above the ground, and as you say, there is also less convection, and what air exchange there is results in the air above actually warming the ground. Now, let's try to examine this in terms of radiative exchange: The radiative temperature of the upper sky is quite cool, as measured with infrared thermometers, and thermal IR is going back and forth bringing the surface into equilibrium with the upper sky. We know that this cooling effect is significant enough to notice, as everyone reading this has felt it at some point in their life. We also know that the upper sky is similarly cool during the day time, and so we also know that the radiative exchange is occurring just as strongly throughout the day. So in the outside environment, solar energy is pumped down and radiated back up throughout the day, and continues to radiate throughout the night. In the greenhouse environment, solar energy is pumped down and almost none of it radiates away, day or night. To explain why the greenhouse is warmer, you must explain why the outside world cools off at night. I challenge you to try to find a reason for that in terms of "convection suppression". — Cortonin | Talk 03:36, 11 May 2005 (UTC)

The units are not sq.m./sq.m., and it does not describe the fraction of window exposed. It instead describes the "air infiltration per unit area of cladding". A more reasonable value for an open surface would probably be 0.0053, as is given in the paper for the open ventillator term. — Cortonin | Talk 05:31, 10 May 2005 (UTC)

I cannot see how this document supports Cotonin's arguement, in fact by my reading so far, it directly contradicts his view. As it emphasizes by what it leaves out, the importance of convection blocking to greenhouse function. -Vsmith 03:42, 10 May 2005 (UTC)

"As it emphasizes by what it leaves out, the importance of convection blocking"? Are you listening to yourself? The paper describes the mechanism of actual greenhouse operation, and compares it to experiment, showing where all the energy flows, and you say that it fails because it doesn't describe it in terms of how you think it operates? There's a bit of logical error in the reasoning there... If you manipulate those equations to consider an environment with no covering, and only unblocked radiative exchange with the sky and open convection through the same area with an environment of the same temperature (as the temperatures would similarly be equal at the start of greenhouse function), then you'll still find that the rate of energy loss to the sky exceeds the rate of energy loss via convection. So the only reason the paper doesn't describe convection blocking as the important mechanism, and instead describes the radiative coupling to the sky as the critical mechanism, is because that's what the derived equations and the experiment show. — Cortonin | Talk 05:31, 10 May 2005 (UTC)

Yup, I listened to myself. And "So the only reason the paper doesn't describe convection blocking as the important mechanism, and instead describes the radiative coupling to the sky as the critical mechanism, is because that's what the derived equations and the experiment show." simply states that they don't describe or consider convection blocking - the reason the don't is that they are starting with convection blocking as a given and working from there. That warm bubble of air has to first be trapped somehow before the "derived equations and the experiment" can do anything. Gotta trap that wild warm bubble before you can analyze & experiment. Vsmith 15:52, 10 May 2005 (UTC)

The thermodynamics of systems are described in terms of energy flow between systems. You are saying "they don't describe or consider convection blocking ... they are starting with convection blocking as a given." In actuality, "convection blocking" is an inverted term, as I tried to explain previously. The correct thing to do is describe convection. Like I said, the thermodynamics of systems are described in terms of energy flow between systems. What is actually correct to describe is the convection between the outside environment and the upper air, because this is the active component, and this is reducing the temperature of the outside environment. And they DO describe all the convection which does occur between the inside and the outside of the greenhouse, and include it in their model. All convection which does occur is included. If you want to somehow extract an inverted concept of "convection suppression", you have to calculate maximum convection and then subtract off the actual convection. It's included, it's just that you're looking for something backwards because you're talking about what's not there, rather than what is. — Cortonin | Talk 17:16, 10 May 2005 (UTC)

This little debate here is probably best exemplified by the section we had considering the gardening greenhouse versus the global greenhouse. You keep trying to say "the temperature is all IR in the global greenhouse, but convection is suppressed in the gardening greenhouse making it hotter," and I keep trying to say, "the effects of the IR are reduced by convection in the global greenhouse, but the gardening greenhouse does not experience this as significantly because it is an isolated system." The difference is, the first one describes what isn't, and the second one describes what is. And the first one is wrong for doing so, because the temperature in the global greenhouse is NOT all IR. Simple radiative flux-balancing calculations with the sun's input show otherwise. On the large scale, the Earth is too cool for the amount of greenhouse effect it is supposed to be experiencing, because there is an active larger scale convection. You have three systems, maybe four, with natural or artificial boundaries, the surface, the air a little higher up, the upper sky, and the inside of the greenhouse. These surfaces are exchanging energy through various mechanisms to various degrees, and to determine their temperatures you figure out which ones exchange in which way. So if you want to describe the effect, describe it in terms of the energy exchange which DOES actively occur. — Cortonin | Talk 17:16, 10 May 2005 (UTC)

(And let me resummarize, that the "convection suppression" argument is also insufficient for the simple fact that it's not always a heating effect, as explained above. When "the air a little higher" is warmer, convection warms and thus "suppressing" that stops this warming, making it cooler than any environment which is able to receive that warming effect.) — Cortonin | Talk 17:16, 10 May 2005 (UTC)

Temporary injunction

Copied here from Wikipedia:Requests for arbitration/William M. Connolley and Cortonin#Temporary injunction:

Since revert wars between the Cortonin and William M. Connolley have continued through this arbitration, both users are hereby barred from reverting any article related to climate change more than once per 24 hour period. Each and every revert (partial or full) needs to be backed up on the relevant talk page with reliable sources (such as peer reviewed journals/works, where appropriate). Administrators can regard failure to abide by this ruling as a violation of the WP:3RR and act accordingly. Recent reverts by Cortonin [11] [12] [13] [14] [15] by William M. Connolley [16] [17] [18] [19] [20] Additional reverts by others involved in these revert wars may result in them joining this case.

--mav 22:44, 23 May 2005 (UTC)

Partial revert explanation

I am making a partial revert, leaving the edits of 128.138.153.229 in place. I'm going to keep the space in the temperature units, since that bot keeps coming along and setting them to that (which I assume conforms to the style guide). No explanation has ever been given for the removal of the RealClimate water vapor data (in fact, it's never even been mentioned even though it has been reverted out perhaps a hundred times). I think it's useful and provides more detail than the existing references, but it's a blog and not peer reviewed, so I will leave it out for now. If someone else reading this finds it useful, I encourage them to add it back. I will include it here for reference:

RealClimate estimated that water vapor contributes between 36-66% in the cloudless case, or 66-85% if clouds are included. The lower bounds of these estimates are the amount of change if water vapor and clouds are removed, and the upper bounds are the remaining greenhouse effect if everything but water vapor and clouds are removed. [21]

In addition, rather than continue to revert "better known", a subjective judgment, to "other", a neutral relationship, I will simply erase that entire portion of the sentence, as it is not relevant. I am also reincluding the the Horticern reference by Joliet et al., as it was published in a peer reviewed journal, Agricultural and Forest Meteorology, and is accessible there by electronic or physical copy for anyone with access to a good library. The Horticern paper describes a detailed model for greenhouse function, including convection, air infiltration, and radiative exchange with the sky, and determines that for typical greenhouse configurations, the influence of radiative exchange with the sky, and its corresponding blockage by the thermal infrared barrier, is the dominant influence on the temperature of the greenhouse, and in particular, overwhelmingly dominant as the greenhouse starts out closest to the temperature of the surrounding environment, as characterized by the parameter q_sky. In concert with that, I am reverting away the section which says that the radiative description of greenhouses is "simplistic", as this is the description present in the detailed model in the peer reviewed literature. I am similarly reverting out the portion which says that greenhouses work by convection suppression, since this result is not found in the model in the peer reviewed literature, even though the effects of air infiltration are included in the calculation (and included in the experimental observations). — Cortonin | Talk 03:12, 24 May 2005 (UTC)

Yet more pointless words

(William M. Connolley 15:15, 25 May 2005 (UTC)) I've reverted Cortonins "partial" revert, since it restores his errors as ever. The literature, as has been said time and again, quite clearly describes the GHE as a misnomer; the Horticern paper remains as irrelevant as ever. There, is that enough words for you Oh Arbitrators? They are the same as they ever were, of course, because this is the same dispute as it ever was, so the mystery of whny you want us to repeat the same old words again and again remains. Do I sound bitter?

Partial revert explanation

No peer reviewed source has been provided for the "[not] the same mechanism" paragraph by WMC, however, the Horticern paper does explicitely describe greenhouse function as a strong function of "sky temperature" where "sky temperature characterizes the long-wave radiation emitted by the sky", making it a physical formulation for describing the thermal infrared radiative exchange between the outside and sky and between the greenhouse and sky. Thus, the peer reviewed material shows that greenhouses DO operate by thermal infrared absorption, not just by metaphor, but by thermal flux equation. (It should also be noted that other literature, such as the Lindzen paper referenced, shows significant reduction of this effect in the global case due to the global-scale convection, which has been noted and described.) — Cortonin | Talk 18:27, 28 May 2005 (UTC)

No peer reviewed source, or any source for that matter, was given for calling CO2 "better-known". Document, or don't make the comparison. I think this sounds about as silly as calling tea better known than water, when the comparison is not at all important to the flow of the article. I will try removing the comparison with CO2 completely, so the paragraph can simply continue discussing the behavior of water. — Cortonin | Talk 18:27, 28 May 2005 (UTC)

I will re-insert the Joliet O., et al. Horticern paper, as it was peer reviewed, describes "an improved static model for predicting the energy consumption of a greenhouse", its removal was not justified, and no later peer reviewed source has been presented which even attempts to refute the paper. And the section on "real greenhouses" is being reverted because the WMC version claims that greenhouses do not operate by function of thermal infrared radiation, which contradicts the peer reviewed literature (the Horticern paper) describing their dependence on thermal infrared radiation interactions both in model and in experiment. No later peer reviewed source has yet been presented which even attempts to dispute this. — Cortonin | Talk 18:27, 28 May 2005 (UTC)

Yet more pointless words

(William M. Connolley 20:32, 28 May 2005 (UTC)) I've reverted Cortonins "partial" revert, since it restores his errors as ever. The literature (hey, lets ref one example of it: Wood, 1909, as has been said time and again, quite clearly describes the GHE as a misnomer; the Horticern paper remains as irrelevant as ever, as Cortonin neatly proves:

the Horticern paper does explicitely describe greenhouse function as a strong function of "sky temperature" where "sky temperature characterizes the long-wave radiation emitted by the sky", making it a physical formulation for describing the thermal infrared radiative exchange between the outside and sky and between the greenhouse and sky. Thus, the peer reviewed material shows that greenhouses DO operate by thermal infrared absorption, not just by metaphor, but by thermal flux equation

See how badly C understands the physics? Of course the T in a greenhouse depends in part on downwards IR radiation. But this is not the point at issue at all. The issue is what happens to the solar energy deposited *inside* the GH, for which the sky temperature is irrelevant.

(William M. Connolley 22:20, 28 May 2005 (UTC)) Also, your attention is directed to this: [22]

Wood's "Communication by the author" is not a peer reviewed publication, and carries no weight compared to a modern peer reviewed experimentally confirmed model. Calling a non peer reviewed essay from 1909 "the literature" is a severe stretch of the word, and even you know that. As for the solar energy inside the GH, what you fail to understand, is that the solar energy deposited inside the GH is almost exactly the same as the solar energy deposited outside, so this alone has nothing at all to do with the temperature of the greenhouse, as there is a complete symmetry between inside and outside of incoming energy. Where the two systems DO differ, is that the outside interacts not just with the sun, but more dominantly with the entire sky, while the greenhouse is largely shielded from coupling to the sky due to the glazing absorbence of that radiation wavelength. This is the physics, I understand it, the Horticern paper describes it in great depth, and you can't dismiss it simply by saying it's "irrelevant". — Cortonin | Talk 06:29, 29 May 2005 (UTC)

(William M. Connolley 10:55, 29 May 2005 (UTC)) Woods paper remains relevant, unlike Horticern. There is a big diff between energy inside and energy outside, namely - its inside! And it has problems getting out, because the fastest mechanism - convection - isn't possible. Once again, we are back to the same old words. The *outside* of the GH does indeed interact with the sky temps (though I rather suspect that Horticern may be thinking about night) but... so what? We all agree that a glass GH is opaque to IR, so repeating this doesn't help. The Horticern paper remains irrelevant.

"though I rather suspect that Horticern may be thinking about night"?? For crying out loud, did you even read the paper? Your comments over the past few months have strongly indicated not. First, nearly every instance of the word "night" in the Horticern paper is in the phrase "day and night" or "daytime and nighttime", because the Horticern paper describes BOTH, as, newsflash, greenhouses exist 24 hours a day, and the physics that describes their operation is operating 24 hours a day, or else all the crops would die overnight. — Cortonin | Talk 18:51, 29 May 2005 (UTC)

Second, the model you keep proposing as "remains relevant" is included in the Horticern paper as the "classical model" type which describes thermal exchange between inside and local outside environment, and it is shown to not only not yield the right predicted results (or seasonal dependence) for the constant, but to not even have the proper functional dependence under a best fit. As I quote from the Horticern paper, "This relation is incorrect when radiative exchange to the external cladding surface is a major part of the total exchange." — Cortonin | Talk 18:51, 29 May 2005 (UTC)

Reverting to match this peer reviewed literature from the modern era of science. — Cortonin | Talk 18:51, 29 May 2005 (UTC)

(William M. Connolley 22:00, 29 May 2005 (UTC)) Crying out loud won't help. You need to understand the physics. Horticern does mix day and night, so you would need to unmix them to use the paper, since we're talking about he time when solar heating is occuring, ie daytime.

Horticern does not "mix" them, it considers BOTH of them. You have failed to consider night, but this is unfortunate, because nighttime offers the clearest example of how the greenhouse functions, because every variable is present which is present during the day except the sun, allowing us to only examine the other energy flows in the greenhouse. (Since we all agree that the sun is present during the day, there is no dispute there.) As Horticern says, "Experimental measurements over a series of nights allowed the hypothesis of a constant specific loss to be tested," which is precisely where they find out that the physical relationship you propose with all thermal exchange being convective, is not the case. — Cortonin | Talk 19:13, 30 May 2005 (UTC)

What also won't help is quoting out of context. The quote you give, above, is from the section discussing the relation U=b+cv. Since we're not talking about windspeed (v) this is thus irrelevant. The "classical" approach, as outlined in Horticern, is to suppose that U is constant.

It's not in the least bit out of context. They're discussing the various models for U, and they go through various other proposed corrections, such as the inclusion of wind influence, and show why they are, and I quote, "incorrect", and then later propose a model for U which is a function of sky temperature, and includes the thermal infrared influence, and then show that this is correct. You have either repeatedly missed this, or chose to ignore it since it did not support the port you wanted to make. — Cortonin | Talk 19:13, 30 May 2005 (UTC)

What would help would be reading the met literature, which it seems you haven't: fortunately there are plenty of quotes in the version I've reverted, such as: Piexoto, JP and Oort, AH: Physics of Climate, American Institute of Physics, 1992 (quote: ...the name water vapor-greenhouse effect is actually a misnomer since heating in the usual greenhouse is due to the reduction of convection). Or perhaps... you think the American Institute of Physics is an unreliable source?

And their detailed thermodynamic model explaining this and experimental confirmation of this are where? Science doesn't work by relying on off-the-cuff comments, it works by detailed theory confirmed by experiment. — Cortonin | Talk 19:13, 30 May 2005 (UTC)

(William M. Connolley 21:44, 30 May 2005 (UTC)) This appears to be your problem: you are trying to do original reseach on wiki. You aren't allowed to. You;re supposed to report what the science says, not what you would like it to say.

(William M. Connolley 21:44, 30 May 2005 (UTC)) So, todays pointless words: Rv again, as justified by, amongst so many others, Henderson-Sellers, A and McGuffie, K: A climate modelling primer (quote: Greenhouse effect: the effect of the atmosphere in re-readiating longwave radiation back to the surface of the Earth. It has nothing to do with glasshouses, which trap warm air at the surface).

Note, BTW, that Cortornins The global greenhouse effect experiences a similar thermal infrared absorption effect to what occurs with the glazing of a gardening greenhouse (Joliet, et al., 1991). is misrepresenting J, which does not (as far as I can see) deal with the global GHE at all.

BTW, up to 4 now: [23]. You are the Black Knight in Monty Python.

Differences and similarities

Version 1

• 1.1: The term 'greenhouse effect' originally came from the greenhouses used for gardening, but it is a misnomer since greenhouses operate differently [24] [25] [26] [27] (Fleagle and Businger, 1980; Idso, 1982; Henderson-Sellers and McGuffie).
• 1.2: A greenhouse is built of glass; it heats up primarily because the Sun warms the ground inside it, which warms the air near the ground, and this air is prevented from rising and flowing away. The warming inside a greenhouse thus occurs by suppressing convection and turbulent mixing.
• 1.3: This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature will drop considerably.
• 1.4: It has also been demonstrated experimentally (Wood, 1909): a "greenhouse" built of rock salt (which is transparent to IR) heats up just as one built of glass does.
• 1.5: Greenhouses thus work primarily by preventing convection; the greenhouse effect however reduces radiation loss, not convection.
• 1.6: It is quite common, however, to find sources (e.g. [28] [29] [30]) that make the "greenhouse" analogy.
• 1.7: Although the primary mechanism for warming greenhouses is the prevention of mixing with the free atmosphere, the radiative properties of the glazing can still be important to commercial growers. With the modern development of new plastic surfaces and glazings for greenhouses, this has permitted construction of greenhouses which selectively control radiation transmittance in order to better control the growing environment.[31].

Version 2

• 2.1: The term 'greenhouse effect' originally came from the greenhouses used for gardening.
• 2.2: The global greenhouse effect experiences a similar thermal infrared absorption effect to what occurs with the glazing of a gardening greenhouse (Joliet, et al., 1991).
• 2.3: The gardening greenhouse is reasonably well isolated from direct convection with the atmosphere and this isolation means that the warmed air is not free to convect out of the greenhouse.
• 2.4: In the free atmosphere convection does play a significant role in global atmospheric heat redistribution. In the absence of atmospheric convection, average surface temperatures would be 72°C, rather than the current temperature 15°C, which is actually closer to the blackbody temperature of the Earth, -18°C, which would occur in the absence of any global greenhouse effect.[32]
• 2.5: This difference in temperatures is because convection facilitates redistribution of heat energy, sometimes raising hot air above much of the greenhouse gases in the same way that convection through a window of a greenhouse would move heat energy outside of the greenhouse.
• 2.6: Energy is redistributed by convection in the global greenhouse effect past the IR absorbent barrier, but very little of the energy trapped by a gardening greenhouse is able to convect past the barrier. This difference is one reason that the term greenhouse effect is sometimes called a misnomer when applied to the global system. [33]

Shuffled

• 1.1: The term 'greenhouse effect' originally came from the greenhouses used for gardening, but it is a misnomer since greenhouses operate differently [34] [35] [36] [37] (Fleagle and Businger, 1980; Idso, 1982; Henderson-Sellers and McGuffie).
• 2.1: The term 'greenhouse effect' originally came from the greenhouses used for gardening.
• 2.2: The global greenhouse effect experiences a similar thermal infrared absorption effect to what occurs with the glazing of a gardening greenhouse (Joliet, et al., 1991).
• 1.2: A greenhouse is built of glass; it heats up primarily because the Sun warms the ground inside it, which warms the air near the ground, and this air is prevented from rising and flowing away. The warming inside a greenhouse thus occurs by suppressing convection and turbulent mixing.
• 2.3: The gardening greenhouse is reasonably well isolated from direct convection with the atmosphere and this isolation means that the warmed air is not free to convect out of the greenhouse.
• 1.3: This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature will drop considerably.
• 1.4: It has also been demonstrated experimentally (Wood, 1909): a "greenhouse" built of rock salt (which is transparent to IR) heats up just as one built of glass does.
• 1.5: Greenhouses thus work primarily by preventing convection; the greenhouse effect however reduces radiation loss, not convection.
• 2.4: In the free atmosphere convection does play a significant role in global atmospheric heat redistribution. In the absence of atmospheric convection, average surface temperatures would be 72°C, rather than the current temperature 15°C, which is actually closer to the blackbody temperature of the Earth, -18°C, which would occur in the absence of any global greenhouse effect.[38]
• 2.5: This difference in temperatures is because convection facilitates redistribution of heat energy, sometimes raising hot air above much of the greenhouse gases in the same way that convection through a window of a greenhouse would move heat energy outside of the greenhouse.
• 1.6: It is quite common, however, to find sources (e.g. [39] [40] [41]) that make the "greenhouse" analogy.
• 1.7a: Although the primary mechanism for warming greenhouses is the prevention of mixing with the free atmosphere, the radiative properties of the glazing can still be important to commercial growers. With the modern development of new plastic surfaces and glazings for greenhouses, this has permitted construction of greenhouses which selectively control radiation transmittance in order to better control the growing environment.[42].
• 2.6: Energy is redistributed by convection in the global greenhouse effect past the IR absorbent barrier, but very little of the energy trapped by a gardening greenhouse is able to convect past the barrier. This difference is one reason that the term greenhouse effect is sometimes called a misnomer when applied to the global system. [43]

Merged

• 1.1: The term 'greenhouse effect' originally came from the greenhouses used for gardening, but it is a misnomer since greenhouses operate differently [44] [45] [46] [47] (Fleagle and Businger, 1980; Idso, 1982; Henderson-Sellers and McGuffie).
• 2.2: The global greenhouse effect experiences a similar thermal infrared absorption effect to what occurs with the glazing of a gardening greenhouse (Joliet, et al., 1991).

  (William M. Connolley 23:05, 29 May 2005 (UTC)) This appears to imply that Joliet talks about the global GH effect. As far as I can see, it doesn't. Its also misleading, as phrased. Acceptable would be "both the atmosphere and the glass of a greenhouse share the property of being largely transparent to SW and largely opaque to LW".

• So you finally admit that greenhouses are opaque to LW similarly to how the atmosphere is partially opaque to LW. Now why do you still think this warms the atmosphere, but not the greenhouse? Obviously if it produces a warming in one, the same physics will produce a similarly increased warming in the other. — Cortonin | Talk 19:22, 30 May 2005 (UTC)

  (William M. Connolley 20:51, 30 May 2005 (UTC)) You are talking voodoo. The fact that the same effect occurs in both is no evidence at all that they of the same importance in both.

• 1.2a: A greenhouse is built of glass; it heats up primarily because the Sun warms the ground inside it, which warms the air near the ground, and this air is prevented from rising and flowing away. The warming inside a greenhouse thus occurs by suppressing convection and turbulent mixing.
• 2.3: The gardening greenhouse is reasonably well isolated from direct convection with the atmosphere and this isolation means that the warmed air is not free to convect out of the greenhouse.
• 1.3: This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature will drop considerably.
• 1.4: It has also been demonstrated experimentally (Wood, 1909): a "greenhouse" built of rock salt (which is transparent to IR) heats up just as one built of glass does.
• 1.5: Greenhouses thus work primarily by preventing convection; the greenhouse effect however reduces radiation loss, not convection.
• 2.4: In the free atmosphere convection does play a significant role in global atmospheric heat redistribution. In the absence of atmospheric convection, average surface temperatures would be 72°C, rather than the current temperature 15°C, which is actually closer to the blackbody temperature of the Earth, -18°C, which would occur in the absence of any global greenhouse effect.[48]

  (William M. Connolley 23:05, 29 May 2005 (UTC)) I quibble this slightly. L is not (as far as I'm concerned) a reliable source for numbers of this kind (the same article contains the 98% wv stuff). I don't say its wrong, just that a better source is desirable, if its right. Although just the first sentence would be fine, unsourced.

• 2.5: This difference in temperatures is because convection facilitates redistribution of heat energy, sometimes raising hot air above much of the greenhouse gases in the same way that convection through a window of a greenhouse would move heat energy outside of the greenhouse.
• 1.6: It is quite common, however, to find sources (e.g. [49] [50] [51]) that make the "greenhouse" analogy.
• 1.7a: The radiative properties of the glazing can be important to commercial growers. With the modern development of new plastic surfaces and glazings for greenhouses, this has permitted construction of greenhouses which selectively control radiation transmittance in order to better control the growing environment.[52].

  (William M. Connolley 23:05, 29 May 2005 (UTC)) Probably needs some qualification as to just how much difference the glazings make, and night/day (for the misnomer stuff its day only). We're in the broad-brush stuff: the effect is "largely" supp-of-conv: commerical growers probably care about shaving 1% off heating costs.

• By "for the misnomer stuff its day only" you of course mean, "WMC's argument only fits intuition during the day, when at night it sounds like nonsense." Of course, this ignores the fact that greenhouses stay warm at night too by the same physics, just as they do during the day, and don't experience the significant cooling which occurs to the outside environment due to radiative exchange with the upper sky. If they didn't have this property, all the crops would die from frost. — Cortonin | Talk 19:22, 30 May 2005 (UTC)

  (William M. Connolley 20:51, 30 May 2005 (UTC)) We're not talking about night time. If you're talking about night time, you're in the wrong discussion.

• 2.6: Energy is redistributed by convection in the global greenhouse effect past the IR absorbent barrier, but very little of the energy trapped by a gardening greenhouse is able to convect past the barrier. This difference is one reason that the term greenhouse effect is sometimes called a misnomer when applied to the global system. [53]

Comparison

Let's try comparing the above text. (SEWilco 21:36, 29 May 2005 (UTC)) Revised (SEWilco 16:27, 30 May 2005 (UTC))

• In 1.2a, an agricultural greenhouse is primarily warmed by heated ground.
  • Is this because a greenhouse has little air, and a greenhouse as tall as the atmosphere may get a majority of warmth from heating of air?
  • Is ratio of heating sources relevant?
  • The greenhouse effect does not address source of heat, but rather loss of heat.
  • The high density, thus thermal storage, of warm solid matter is relevant to keeping an ag greenhouse warm at night.
  • The same warm solid matter can keep the greenhouse warm due to not having to warm all the atmosphere above.
• Both versions agree that an agricultural greenhouse blocks convection.
• In 1.4 it is claimed that an IR-transparent greenhouse still heats up.
  • Has this experiment been reproduced reliably?
  • Does an IR-transparent greenhouse cool differently? (ie, at night)
    • The Takakura paper describes behavior of some plastic films which are IR transparent.
• In 2.5 it is claimed that the atmosphere has convection outside the greenhouse area.
  • Most of the mass of the atmosphere is near the ground.
    • Does most of the atmospheric warming happen near the ground?
    • Does most of the atmospheric greenhouse effect happen near the ground?
  • General atmospheric circulation brings warm air to high altitudes.
    • Is there sufficient greenhouse effect at high altitudes to block IR escape?
  • What is described is the lower atmosphere being like an IR-blocking greenhouse, with its warm air circulating through a surrounding IR-transparent structure (the upper atmosphere).
• In 2.2 the IR blocking by glazing is invoked in comparison with atmospheric warming.
  • This invocation connects both warmings and enhances importance of IR blocking.
  • Remove this phrasing to break the connection, and let the two stand on their own merits.

Re: Comparison

Here are some online references that may help:

• How do greenhouses work? by Sue Ann Bowling, a professor of physics at the Geophysical Institute. She provide a simple, clear explanation in layman's language.
• Physics of the Greenhouse Environment, by T. Takakura et al. (originally published in the Proceedings of the American Society for Plasticulture, and later in the newsletter of the Center for Controlled Environment Agriculture. It states, in part, "The so-called 'greenhouse effect' is a very misleading term. Although the term originated from the greenhouse itself, the higher temperature in a greenhouse is not due to the same effect which is predominant in global warming. ... Thick films seem to be effective as heat barriers, but convective heat transfer resistance of the air inside the greenhouse is a much larger factor than the resistance to heat flow through a film. ... Businger (1963), who studied the greenhouse physical environment, demonstrated the amount of warming due to the greenhouse effect by steady-state analysis. His conclusion was that this radiation absorbed by the covering accounts for only 20 to 30% of the warming in a greenhouse, and the main cause of warming is a lack of ventilation in the greenhouse. One of the definite supporting studies is the experiment in 1900 by Wood in which he compared two model greenhouses." (The Wood paper, of course, is the one that WMC has also been citing.) --Sheldon Rampton 22:05, 29 May 2005 (UTC)

(William M. Connolley 11:15, 30 May 2005 (UTC)) Thanks for these Sheldon. The first is a nice clear for-the-public exposition. The second seems about as clear a statement as you could wish, and its a paper from the american institute of plasticulture, so perhaps will satisfy Cortonins need for something outside the met literature.

I've seen the Takakura paper before. It, first of all, was not peer reviewed, as it was only an abstract presented at a preceeding, which are typically not peer reviewed prior to printing (and neither are newsletters peer reviewed, which was its second appearance). This is important, because if it had been peer reviewed, maybe someone would have noticed that he, extremely incorrectly, argues against thermal photoselectivity of films by plotting the transmittivity of films up to 1200 nm, which is a wavelength range an ORDER OF MAGNITUDE too small to represent thermal infrared transmittivity (on the order of 10,000 nm). A peer reviewer might have caught that, I would hope, which is why we benefit from using peer reviewed material instead when it is available. — Cortonin | Talk 18:58, 30 May 2005 (UTC)

In addition to this rather significant oversight which encourages him to incorrectly ignore the thermal infrared contribution, his plot in figure 1 does not show what he claims it to in the text when he writes "20 to 30% of the warming". He examines the resultant calculated temperature at various windspeeds, and then attempts to deduce that windspeed is causing the temperature. Consider an experiment with an oven in a wind-tunnel, where someone measures the temperature of the oven at various windspeeds, and then deduces, "Only 20-30% of the warming in the oven is due to the heat from the coils, the rest is due to there being no wind." Would this be right? It is a logical fallacy (argument from inverse) to draw this conclusion, and it results in many incorrect conclusions, of which this is one. It is no different with the greenhouse, and no different in the description given in this newsletter. I'm sorry if that violates the intuition of everyone who would like argument from inverse to be valid, but it is not. — Cortonin | Talk 18:58, 30 May 2005 (UTC)

Revert Explanation

Each point raised has been responded to with explanation, and the Horticern paper remains the only peer reviewed paper presented describing a detailed experimentally-confirmed description of greenhouse operation, and it describes thermal radiative exchange as criticial to the operation of the greenhouse, with sky temperature a critical variable, so I am reverting to the version which does not rule that out, and which includes reference to the Horticern paper. — Cortonin | Talk 19:27, 30 May 2005 (UTC)

Another ref

Newell 1970 [54] sources it to Kondratyev 1965. Just adding it here so I can find it if needed William M. Connolley 13:21, 7 June 2007 (UTC)

Greenhouse effect in real greenhouse

I'd like to raise some discussion about is the real greenhouse actually working based on greenhouse effect:

Energy transmissed from ground by thermal radiation at 20 degrees Celsius:
Eb = σT4

  = 5,67·10-8W/m2K4 x (293^4)

  = 417,8818804 W/m2

Energy transmissed by thermal convection is highly dependant on temperature difference. Let's calculate what is the thermal convection when ground temperature is 25 and air temperature is 20: a when no wind (like inside greenhouse) ~ 5 W/m^2K
E = a(T1-T2)

 = 5 *(25-20)

 = 25 W/m^2

Is the only argument on greenhouse warming up mainly by convection based on this R. W. Wood experiment from 1909?: http://www.wmconnolley.org.uk/sci/wood_rw.1909.html —Preceding unsigned comment added by 213.216.199.26 (talk) 21:11, 24 March 2008 (UTC)

404 on first link

link to "Intergovernmental Panel on Climate Change Fourth Assessment Report. Chapter 1: Historical overview of climate change science" is: http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch01.pdf not http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Pub_Ch01.pdf

I know it's already been in debate, but since this link does not exactly state "greenhouse effect" as a misnomer, maybe wikipedia article should be somewhat more subtle? Eric DUMINIL 07:54, 30 October 2007 (UTC)

I don't intend to be rude but since I have been reading about greenhouse effect since 1980 and I can't make sense out of any of the schematics (or even the article) and since I am fully aware of Exxon's budget on total disinformation.

I once prepared a course on solar energy... and I just legimatly wondered if this article had been sabotaged (if the CIA can edit wikipedia...).

So I have suggestions applying for honest editors as well as for humandkind killers :).

Why don't you start with a physical drawing of the rays with reflected and transmitted rays. In paralell to it make a servo system type of energy flow with summing nodes and + and - signs.

The exchanges of energy shown does not add up so it is impossible to understand. There should be a large paragraph dedicated to it.

The solar radiation spectrum : to be easier to understand many changes are needed.

The title should say radiation spectrum, since it is not only solar. The Y axis label could read "watts per quare meter" to be clear for anybody without lying.

The UV, visible and IR indications do not need to project dotted lines down so far to reduce clutter. It could be a bar showing gradated colors only at the top of the graphic.

Then the absorbtions bands labels could be made uniform.

Instead of using red text to point at yellow, black and red parts I suggest a small legend at the upper right.

Change to µm would reduce clutter (might help clarify the absorbtions) and also would ease to see relations with the transmission graphics below.

The transmission graphics need similar simplifications. The blackbody curves do not serve anybody's understandment since there is no reference about it in the text. —Preceding unsigned comment added by 70.83.31.41 (talk) 03:14, 3 January 2008 (UTC)

Re-write

I saw a really clear and precise explanation of the greenhouse effect at a website. But I hesitate to rely on it without some checking from the Anome or Axelboldt or anyone else who really knows the science.

of all the sunlight that passes through the atmosphere annually, only 51 % is available at the Earth's surface to do work. This energy is used to heat the Earth's surface and lower atmosphere, melt and evaporate water, and run photosynthesis in plants. Of the other 49 %, 4 % is reflected back to space by the Earth's surface, 26 % is reflected to space by clouds and atmospheric particles, and 19 % is absorbed by atmospheric gases, particles and clouds. [55]

(William M. Connolley 22:07, 8 Sep 2003 (UTC)) Yes. But this isn't a description of the GH effect. Its a picture of how solar radiation is distributed through the atmos. But I've used it in my re-write.

I like the percentage breakdowns [But they are illustrative only: they would vary strongly in space and time. WMC]. The mention of clouds is especially interesting, because one theory is that higher temperatures will evaporate more seawater and increase cloud cover. This would increase the percentage of solar radiation reflected by clouds and decrease the percentage that hits the earth's surface. Could this be a self-regulating effect of the atmosphere? Does the greenhouse effect come with a "thermostat"?

The percentage breakdowns are generally misleading because different numbers (for water vapor for example) are listed from different sources, but these different sources use different definitions -- these differences are almost entirely semantic, and yet the text gives the impression of great uncertainty on how to compute radiative transfer. In fact, there is almost no uncertainty in radiative transfer. I have added a sentence to this effect as a placeholder Climateguru

Maybe it depends on how much warming is causd by trace gases, and how much cooling is caused by increased cloud cover. Has anyone studied that? (How about the IPCC, since they're such highly regarded experts?) --Uncle Ed 17:07, 8 Sep 2003 (UTC)

---

(William M. Connolley 22:07, 8 Sep 2003 (UTC)) I have done a major re-write of the how-GH-effect works section, using the model I like, from the "bad greenhouse" page. This has now relegated the former explanatory link to a terrible example of how to get it wrong. Sorry. The text is somewhat untidy and perhaps over-pernicity in places, I look forward to its evolution.

---

The first paragraph currently reads:

The clearest and most direct way to understand the "greenhouse effect" is to see that the surface of the earth is warmed by two sources: the sun, and the atmosphere [1]. It is thus warmer than it would be in the absence of the atmosphere.

I think this description is so simplified that it doesn't explain what the greenhouse effect is. If the atmosphere reflected most light at the sun's peak frequencies, but was mostly transparent to infra-red radiation corresponding to the surface temperature, it the earth would still be warmed by the same two sources. But in this case the surface wouldn't be warmer than it would be in the absence of the atmosphere, would it?

Matthew Woodcraft

(William M. Connolley 13:38, 8 Nov 2003 (UTC)) I wrote that para, in contrast to the wurbley stuff about "insulation" that was there before.

I don't understand your example. If the atmos reflected most solar, then there would be little heat input to the system, and the whole thing would cool. If the atmos was mostly transparent to IR, then it wouldn't emit in the IR, so it wouldn't heat the earth.

So I think the first para is OK, though simplified (it doesn't explain how the atmos comes to be warm, for example).

Well, the first paragraph currently states (by saying thus) that an earth with an atmosphere will necessarily be warmer than one without an atmosphere. And that's just false, isn't it?

Well, it could be, if the atmosphere were entirely transparent to radiation. But in an atmosphere roughly resembling ours (largely transparent to viz (and thus heated from the bottom), somewhat opaque to IR) its true. This is currently explained in para 4 at the moment. Why do you think its so false?

Because by saying The clearest and most direct way to understand the "greenhouse effect" is..., it suggests that it's giving a sufficient explanation. But the effect relies on particular properties of the atmosphere which aren't obvious, and aren't mentioned in the proposed explanation.

It also seems to me that without explaining how the atmosphere gets to be warm, it doesn't really count as a description of the greenhouse effect. Perhaps there isn't room for a description in the first paragraph. How about opening the article by just saying that the greenhouse effect is the name of the phenomenon by which the atmosphere warms the earth, and leave explanation for later? Matthew Woodcraft

You're welcome to try to improve it. The reason the actual physics is up there at the front is that its so common to see dubious non-physical explanations up front. I wouldn't want to see the explanation buried.

Ok, I've had a go. Matthew Woodcraft

---

(William M. Connolley 12:42, 9 Nov 2003 (UTC)) I quite liked MW's new very simple first para, which on reflection was nice and accurate. I've changed Mav's non-earth-centric stuff somewhat, so that it notes other planets but then only talk of earth. Because: all the rest of the article is about earth; and I don't think you can be completely general anyway (imagine the case of a star so dim it mostly radiated in IR, for example; or a planet whose atmospheric composition was v different). Oh, and lower down, I've sneaked in a change from global warming hypothesis to global warming, because gwh is currently a rather poor page.

The fact that this article concentrates on the Earth is a major disservice to the reader. The greenhouse effect is a general phenomenon and should be discussed as such with examples given from (and comparing/contrasting) the present and past effects on the Earth, Mars, Venus, other astronomical objects (such as moons) and laboratory settings (not to mention the effect in actual greenhouses!). So that is what should be concentrated on in regards to expanding this article. When the article then gets large enough, then the Earth-specific stuff can and should be summarized here and moved to a daughter article. --mav 23:24, 9 Nov 2003 (UTC)

Well, OK. But I know nothing about GH on other planets, so I'll leave that to those who do!

The little I know about the "greenhouse effect" is that having an atmosphere on a planet helps insulate it. So it tends to (a) avoid rapid fluctuation of temperature as it rotates every day and (b) is quite a bit warmer than it would be without atmosphere. Venus and Earth are the main examples, although science fiction writer Robert A. Heinlein extended the concept to Ganymede for Farmer in the Sky.

I don't care how much or little we generalize, although I'm inclined to follow mav's suggestion just because I trust his judgment. The main thing is that the greenhouse effect be based on known facts; and that what is known about this effect not be confused with speculation about the "runaway greenhouse effect" predicted by some pro-Kyoto environmentalists. --Uncle Ed 16:51, 10 Nov 2003 (UTC)

---

WMC commented in History: "60-70 from ipcc '90 (would be better from TAR)". Good idea, please do insert the water vapor percentage from TAR. (SEWilco 09:57, 13 Dec 2003 (UTC))

New Articles: Global climate change and Climate forcings

Please read the new articles and consider commenting on them and/or moving some material to either one. Note that climate forcings is not specific to global climate forcings, so if it makes sense to create a separate section please do.

I hope this helps get this part of Wikipedia sorted out.

Posted to all discussion pages listed in the "See Also" section of global climate change. --Ben 03:48, 2 Dec 2004 (UTC)

Lindzen quote

Removed the following:

For a theoretical case if no other greenhouse gases were in the atmosphere, Richard Lindzen estimated 98% (Global warming: the origin and nature of the alleged scientific consensus. Regulation, Spring 1992 issue, 87-98 [56]).

as it is an unsupported quote from a Business & Govt publication. Seems rather an irrelevant statement. -Vsmith 16:24, 10 Apr 2005 (UTC)

For the estimate of what percentage greenhouse effect would remain if carbon dioxide were removed, I've seen numbers of 85%, 88%, 90%, 94%, 95%, and 98%. For the 98%, I think Lindzen may include atmospheric convection feedbacks, but I'm not sure. Is the 98% an extremum? Yeah, definitely. It's on the edge of the numbers I've seen, in the list there. 5.8 degrees of predicted warming is also an extremum outside of the mainstream calculations, but we include that too. The NPOV policy instructs us to include prominent information that can be attributed to prominent groups or individuals, and this certainly qualifies. — Cortonin | Talk 18:56, 10 Apr 2005 (UTC)

I modified the tone slightly, since it's not clear precisely how he calculates this number, and I presented the atmospheric convection feedback alluded to by the surrounding text in the reference. It is a frequently quoted number, so its absence will only warrant its inclusion later. — Cortonin | Talk 19:31, 10 Apr 2005 (UTC)

To obtain this estimate, he may have included various theorized atmospheric feedbacks. and he may have just pulled it out of his hat - seems a bit odd to add our interpretations or suppositions (isn't that akin to orig. research?). I don't think the NPOV policy means that we must include all prominent info no matter how questionable or irrelevant. To me this extremum is both questionable and irrelevant as we don't have direct info on how the number was derived or imagined. Therefore, I say begone with the meaningless tidbit. Vsmith 02:56, 11 Apr 2005 (UTC)

(William M. Connolley 08:59, 11 Apr 2005 (UTC)) I too say begone with it. For one thing, For a theoretical case if no other greenhouse gases were in the atmosphere is my words, not his - and I realised they were wrong. If anyone wants the 98% value in, it needs to be (a) properly sourced (to science, not Cato) (b) correctly described.

Here is a little more reading. [57] (SEWilco 20:29, 11 Apr 2005 (UTC))

• "4. CO2 contribution to the ~33°C natural greenhouse effect
  • Lindzen: "Even if all other greenhouse gases (such as carbon dioxide and methane) were to disappear, we would still be left with over 98 percent of the current greenhouse effect." Cato Review, Spring issue, 87-98, 1992; "If all CO2 were removed from the atmosphere, water vapor and clouds would still provide almost all of the present greenhouse effect." Res. Explor. 9, 191-200, 1993.
  • Lacis and Hansen: removing CO2, with water vapor kept fixed, would cool the Earth 5-10°C; removing CO2 and trace gases with water vapor allowed to respond would remove most of the natural greenhouse effect."

(William M. Connolley 21:17, 11 Apr 2005 (UTC)) Thanks. OK, so for Lindzen, thats the same non-sourced thing again (Cato), except it is clear now that he includes clouds rather than just GHGs (Res Explr, whatever that is: who is the author?). So its now quite clear that asserting that WV causes 98% of the GHE is wrong, even from Lindzens numbers. But we don't know what Res Explor actually said or who wrote it.

the icecaps are going to melt and we are going to die in short talk

Yet more tedious septic nonsense

yet another anon added:

The greenhouse effect due to Carbon Dioxide is in dispute and any claims that atmospheric H₂O contributes less than 95% to the greenhouse effect should be suspect. The actual effect of carbon dioxide is closer to 1-2% otherwise Mars' mean temperature would be substantially warmer due to having 13 times as much Carbon Dioxide by mass than Earth. Mars has an atmosphere containing over 95% CO₂ while Earth has roughly 1/30th of 1% CO₂ (ImYourDragon@aol.com)>>

This is the same old tedious nonsense so I've removed it. Notice the characteristic lack of sources; unlike the figures already in the article... William M. Connolley 22:03, 23 December 2005 (UTC).

05:46, 22 March 2006 (UTC)~An Accurate CO2 Percentage?05:46, 22 March 2006 (UTC)~

Sorry, I am not sure how to fully do this, but:

Water Vapor has an IR absorbtion rate of 1, CO2 is also 1, where are Methane has an absortion rate of 32. According to the IPCC.

Water Vapor makes up about 1% of the atmosphere, where as CO2 makes up .03768% (according to Wikipedia.) While I realize the amount of water varies from place to place, the difference is alot closer to 95% than 60%.

I don't think CO2's contribution of 21% to the greenhouse affect is anywhere close to correct. It should be closer to 3.2%. Have a reference?

(Josh Coray)

U.S. Department of Energy (Recent Greenhouse Gas Concentrations) says that CO2 377.3 ppm. Can anyone check the concentration for water vapor? Anyone may call me a skeptic, but to my opinion, there is greater correlation between sun activity and global warming than CO2/Meth emissions. I.e. Effects of CO2 in global warming

What surprises me, is how full of weird science is going on right now. I mean, when looking at graphs of CO2 levels, they are usually from weird places like "Manalulu" or whatever (probably vulcanic). I dont see any clear information like: temperatures in various countries vs their CO2 concentration.

The whole global warming hype is built on top of the assumption: lets assume MAN-MADE CO2 is causing temperature rises due to the greenhouse effect. What amazes me is that at the very kernel of the theory, people are still arguing about the concentration of CO2 in respect to water...

If this is wrong, it would mean that the effects of human CO2 on global warming would be reduced to almost null. I have read the IPCC reports... and well, I and still not convinced about this central issue, that must be cleared. And no, its not being skeptical, I am being scientific. (christian Frahm)

This is wrong on so many levels that it's hard to know where to start. The concentration of CO2 is around 385 ppm. Concentration of water vapor is highly variable -- think Sahara Desert versus the Indonesian rainforest. But in the end, that's mostly irrelevant because the radiative effects of two different gases doesn't depend on their relative concentrations: the gases absorb in different wavelength bands (with a bit of overlap, which is accounted for in all climate models). So, comparing the concentrations of H2O and CO2 is the wrong starting point. Raymond Arritt 17:53, 29 March 2007 (UTC)

I am confused. All that is relevant are gases having a significant absorption in the region of 12 microns, corresponding roughly to the black body temperature of 288K, but10-14microns is an atmospheric window, which why it is widely used by used by thermal imagers. The diagram of atmospheric absorption presented in the article shows that neither CO2 nor water vapour have much effect, CO2 appears to absorb in the 12-20 micron region, whilst water vapour appears to absorb both above and below this region. Since there are no scales on the vertical axis it is difficult to conclude anything from this diagram. If these are extinction coefficients for the gases, then the diagram would indicate that water vapour would have a much greater effect than CO2, if they represent the proportion of absorption due to typical atmospheric concentrations of the two gases, then the effect of CO2 is spectacularly greater than that of water vapour. Could somebody please clarify this.Gordon Vigurs 20:48, 7 September 2007 (UTC)

Runaway?

The article says...

The use of the term runaway greenhouse effect to describe the effect as it occurs on Venus emphasises the interaction of the greenhouse effect with other processes in feedback cycles. Venus is sufficiently strongly heated by the Sun that water is vaporised and so carbon dioxide is not reabsorbed by the planetary crust. As a result, the greenhouse effect has been progressively intensified by positive feedback.

I've never felt very happy with this. Venus has a large GHE because it has a deep atmos with lots of CO2 in it. runaway doesn't obviously have much meaning. And the last sentence implies change but AFAIK nothing much there is changing. William M. Connolley 21:21, 7 January 2006 (UTC).

Maybe add that Venus also has 90 times the atmosphereic mass, of which 96.5% is CO2, and that it receives about twice as much energy meter as the earth? Just for a reference. That might help put it in perspective.

Josh Coray

OK there were some misconceptions in the original framing of the paragraph. The runaway phase is now pretty much over - most of the CO2 has been outgassed from the crust and the water vapour lost. The runaway greenhouse theory is pretty mainstream as an explanation of the difference between the atmospheres of Earth and Venus - it is not about what is happening but how it got wher eit is. Unfortuately, the distinction between the current situation and the process leading to it is sometimes lost in popular science. I've tried to improve it but I think this could be further improved - another thing to add to my list (although I'll have to find some better references than I could by googling).--NHSavage 21:29, 13 May 2006 (UTC)

I'm dubious about closeness-to-sun mattering much (given the high albedo) William M. Connolley 22:14, 13 May 2006 (UTC)

As I say, I need to do more research on this one but the conventional argument is that this is about the goldilocks effect, (Mars is too cold, Venus too hot and Earth just right...) or the Habitable zone and Venus is just too close to the sun to be able to retain its water vapour. I have some questions about this given that the articles seem to argue that the ozone layer is important to prevent UV dissociating water but we did not have an ozone layer until we had oxygen from plants. Still AFAIK it is really not controversial, although the timescale over which venus lost its water and whether there was liquid water for any length of time on Venus seems to still be the subject of active research. The whole idea probably deserves its own article which I might do sometime....--NHSavage 11:53, 14 May 2006 (UTC)

OOps - sorry, just re-read the article and the bit about closeness to the sun is not in the runaway section is it. I think my remarks above are not wrong just off the point. OK - yes I agree that the albedo will also be important. I suppose the question is - if you have a planet with the same orbit as Earth and the same amount of CO2 in its atmosphere as Venus how hot would it be? It would obviously be somewhat cooler than Venus but I don't have the tools to do a calculation as to how hot. I would guess it would be pretty deadly though (apart from the pressure and CO2 themseleves which alone are deadly...)--NHSavage 12:13, 14 May 2006 (UTC)

Closeness to the Sun does matter for Venus, combined with its weaker gravity. This means water vapor rises higher into the upper atmosphere where the Sun's UV radiation breaks it into atomic hydrogen and oxygen. The Hydrogen then escapes into space. This is why Venus no longer has any oceans. This doesn't happen on Earth. (I got this from Scientific American, but I don't know the issue.) -- MiguelMunoz

The article says:

On Earth, x for water vapor is thought to lie in the range 0.3–0.4, so the Earth is far from this runaway condition, as is also self-evident from the stability of the climate through geological time.

This is a too strong assertion, because the above simple series doesn't take into account any other feedback than water vapor.Touisiau 21:32, 21 November 2006 (UTC)

Obviously, this series is a ridiculously too simple model for Earth. This is obviously not a valid model for Earth. How can you say it is "self-evident" that such a model a valid by looking at Earth history ? It would be plain wrong to say that because no runaway effect happened in the past, all simple models that allow absolutely no runaway effect are "self-evident" models for Earth.

The model is a toy explanation of how you can have a positive feedback without having a runaway positive feedback. Of course it is simplified, and I'm sure there are more complicated models, but the point that not all positive feedbacks will runaway is something many people have trouble with, and that is what this is meant to address. The geologic evidence, though only tacked on at the end, is almost certainly the stronger argument. The Earth has had CO2 much much larger than present day without ever ending up looking like Venus. Dragons flight 01:02, 22 November 2006 (UTC)

So the article says we have 2 different reasons to think we are not "near" a runaway: a toy model, and Earth history. First, it should be made clear in the article that the model is a toy model and as such can't be made "right" or "wrong" by earth history. About history: water and CO2 are not the only parameters. Has the planet ever been exactly in the same state as today ? What about its state when all the fossil fuels and rainforests will be burnt ? What about the speed at which those are burnt? "If something did not happen in the past, it can't happen in the future" is not valid for complex models.

It seems to me that two gases are not necessary for positive feedback. I think the article's example of positive feedback in temperatures with water vapor should not mention carbon dioxide. The idea is that if earth's atmospheric temperature were raised by a certain amount (by whatever causes -- CO2, or whatever), then the increased amount of water vapor would raise the temperatures more, which would cause more water to evaporate, etc. If there are no objections, I'll change this accordingly. As for the series -- no, it's not perfect, but to a first order approximation I think it is the right idea. Kier07 05:03, 2 January 2007 (UTC)

"How to kill (almost) all life: the end-Permian extinction event" , Michael J. Benton and Richard J. Twitchett, Department of Earth Sciences University of Bristol UK, TRENDS in Ecology and Evolution Vol.18 No.7 July 2003, http://cat.inist.fr/?aModele=afficheN&cpsidt=14972304

Just check scholar.google.com, this recent article has been cited by 21 articles, especially to confirm the positive feedback loop involving gas hydrates liberated by warming. http://scholar.google.com/scholar?q=how+to+kill+permian&hl=en&lr=&ie=ISO-8859-1&btnG=Search

Such a recent and cited article, which does use the term "runaway greenhouse effect" should be cited in this section.

There are several probs with that ref. First, its ecol+evol. Which is *not* a good place to be looking - it will only be reporting other stuff. Secondly, this isn't the same sense of runaway - its about gas hydrates, which is different. And thirdly, it doesn't assert it as a certainty, but only one of several possibilities. And fourth, its new, which is bad William M. Connolley 23:13, 22 November 2006 (UTC)

Can you provide references to back all your claims ? I am not convinced by any of them (especially the "new" for a 2003 article cited by 21 other articles, since models keep improving in climatology). Touisiau 23:23, 22 November 2006 (UTC)

There is a significant problem with the Permian-Triassic extinction event as a landmark positive feedback CO2 warming event. The P-T boundary about 251 million years ago coincides with the galactic cosmic ray flux minima of the past 600 million years, and that temperature spike tends to support the Svensmark cosmoclimatology model over CO2 feedback. See figure 8: http://www.spacecenter.dk/research/sun-climate/Scientific%20work%20and%20publications/resolveuid/86c49eb9229b3a7478e8d12407643bed Ggoodknight 00:15, 16 August 2007 (UTC)

That's a s t r e t c h...

1. The time spans Shaviv publishes between the high CRF periods are ~ 90, 90, 140, 130, 190, 140 million years. The periodicity of "143±10" seems whimsical. The mean is 130. 143 is greater than 5/6 of the periods.
2. The agreement between the absolute timing of the meteorites and the CRF has meteorite gaps at 100, 190, 280, and 420 million years ago and CRF maxima at 30, 170, 360, and 470 million years ago, and meteorite clusters at 140, 250, and 360 million years ago and CRF minima at 80, 250, and 420 million years ago. Again, the agreement seems whimsical. One of the meteorite gaps lines up perfectly with one CRF minimum, and one of the meteorite clusters lines up perfectly with one CRF maximum, the opposite of what is being postulated, while only one cluster lines up with a minimum as the alignment would predict.
3. Shaviv states that the final cosmic ray model chosen is the one "which best fits the ice age epochs".
4. Even so, the CRF model used in his later papers to match the ice ages is not the same as either of the two different CRF models originally derived, although that paper is listed as the citation. The original CRF curves have a CRF maximum near 360 million years, while that in the ice age paper has a maximum near 320 million years.
5. The CRF maximum is then shifted again, to 300 million years, "fine tuned to best fit the low-latitude temperature"; this final curve has a .81 correlation between cosmic rays and temperature. But even the most recent untuned curve, with the maximum at 320 million years, has no significant correlation, let alone the curves further back in the process, including the original meteorite cluster data vs. historical temperature. This strongly suggests that the perceived correlation is entirely the product of adjusting the data for no other reason than to make it correlate, as is expressly stated.

http://www.pik-potsdam.de/~stefan/Publications/Journals/rahmstorf_etal_eos_2004.html Gzuckier 17:04, 17 August 2007 (UTC)

The relationship between moisture-capacity and temperature is not just linear; as temperatures increase, moisture in the atmosphere increases exponentially. As water vapour is a large constituent of greenhouse gases ( 36%), it becomes increasingly harder for the Earth to cope with the warming effects of water vapour. --Diego Bank (talk) 22:07, 1 January 2008 (UTC)

too narrow a definition?

My understanding has been that if a car's windows are left closed on a hot sunny summer day and the interior of the car heats up, or if the interior of an actual greenhouse warms up in the same way, those are instances of the greenhouse effect (and indeed, the latter example is why it's called the greenhouse effect). But the first paragraph of this article seems to say it's the greenhouse effect only if it's applied to the planet as a whole. Michael Hardy 01:43, 4 March 2006 (UTC)

See the section Real greenhouses at the end of the article. Also if you like old controversy check out the edit wars of last spring - it was a bit tedious. :-) Vsmith 03:29, 4 March 2006 (UTC)

05:57, 22 March 2006 (UTC)24.17.159.58 05:57, 22 March 2006 (UTC)Just a note05:57, 22 March 2006 (UTC)05:57, 22 March 2006 (UTC)

Image:Spectrum of blue sky.gif

Removed Image:Spectrum of blue sky.gif as it was redundant with image already in the article. Initially mis-read the caption. Vsmith 13:17, 13 May 2006 (UTC)

links

website at bottom is incorrect

what cryptic message is this, come upon us as from the oracle, to vex our minds with contrary incomprehensions? Gzuckier 19:48, 31 May 2006 (UTC)

Style change in introduction feels confrontational

I just read the introduction, and I think there is a style change that spoils the flow of the article. The first few sentences come across as you would expect for an encyclopedic article on a scientific subject, being dispassionate and stating or explaining facts. The change comes with: "No-one disputes the former, or its magnitude; the latter is accepted by a large majority of scientists, although there is some dispute as to its magnitude (see scientific opinion on climate change and attribution of recent climate change)." - this sounds like what it is, an attempt to forestall editors who might want to tweak the wording of this article, or turn it into a diatribe on global warming. This was probably done with the best of intentions, but as it stands, the wording sticks out like a sore thumb and significantly detracts from the value of the article. I would like to try and improve that part of the introduction, but wanted to find out if anyone agrees with me about the need to rewrite that sentence. So, does anyone think that sentence needs rewriting? Carcharoth 21:21, 23 June 2006 (UTC)

I strongly disagree that the wording detracts from the article. If you want to try to improve it, feel free, but bear in mind this is a controversial topic and that wording has survived for a fair while. I don't see any need to improve it William M. Connolley 21:30, 24 June 2006 (UTC)