Talk:Rainbow/Archive 2

Archive 1

Archive 2

Archive 3

Rainbow arc shape

Is the arc of a rainbow the portion of a "bubble" that we can see? The bubble would occur because a pocket of air having a lower (or higher) temperature and relative humidity is in contact with the predominant air mass with a different temperature and relative humidity. Has anyone ever explained the arc? — Preceding unsigned comment added by 76.118.153.139 (talk) 15:44, 16 July 2012 (UTC)

No. See the article for details of how a rainbow is formed. Neil Dodgson (talk) 17:38, 16 July 2012 (UTC)

Splitting the article? 2

I am thinking again about splitting this heterogeneous article into two separate articles, Rainbow (physics) and Rainbow (culture), as discussed on the Talk-page before (here). It is easy, almost no editing would be required because Culture is already a single section. We could rename the current article to Rainbow (physics) (keeping its history), move the entire culture section into the new article Rainbow (culture), and create a redirect page for redirecting Rainbow to Rainbow (physics). The above LGBT rainbow flag discussion would then be at home in culture. Ceinturion (talk) 10:23, 2 August 2012 (UTC)

Seems a fair idea. I would take care, however, over differentiating between a rainbow (the meteorological phenomenon) and light spectrum (the division of light into different wavelengths). One is caused by the other but is not necessarily the same topic. Using "(physics)" in the title may confuse the two. --Escape Orbit ^(Talk) 10:47, 2 August 2012 (UTC)

So you think Rainbow (meteorology) is better than Rainbow (physics)? That's fine with me. Ceinturion (talk) 17:52, 2 August 2012 (UTC)

Seems the right time to do it. We had a big clean-up of the Culture section a few years back because it had got so cluttered and some felt that it didn't fit with the physics-slant of most of the article. Neil Dodgson (talk) 13:30, 4 August 2012 (UTC)

If the article should be split I think the name of the physics/meteorology article should be Rainbow since that is the part about the rainbow itself. The culture part could then be moved to a new Rainbows in culture article since that is not directly about the rainbow. I don't see a reason for a disambiguation page since the word rainbow only has one meaning. Wether the article should be split or not I don't know. Ulflund (talk) 14:45, 4 August 2012 (UTC)

Agree on the split if we're voting. There might be a line or two in the science article about "rainbows in popular culture" with Rainbow (culture) as the main article. The science article could be rainbow or rainbow (science) or rainbow (physics). I don't much like rainbow (meteorology) since then we have no place for artificially produced rainbows and rainbow effects not due to weather. A rainbow isn't like rain, lightning and hurricanes, which are all (by definition) weather phenomena, and get different names when produced artificially. SBHarris 18:05, 4 August 2012 (UTC)

I prefer Rainbow (science), because the section about the number of rainbow colors perceived by the human eye is biology (or psychology) rather than meteorology or physics. Ceinturion (talk) 07:12, 7 August 2012 (UTC)

Why not just rainbow? This is definitely the primary topic (WP:PRIMARYTOPIC) for the word rainbow. Ulflund (talk) 10:57, 7 August 2012 (UTC)

I moved the culture section to a new page, Rainbows in culture. Ulflund, my reason for renaming the article to Rainbow (science) would be to prevent sections about cultural aspects to be added again after a while by users who think cultural aspects are part of the primary meaning. On the other hand, the first line of the article is clear that it is about the optical and meteorological phenomenon. And nearly all incoming wikilinks refer to the optical/meteorological phenomenon (which is a criterion in WP:PRIMARYTOPIC). I haven't decided yet. Ceinturion (talk) 10:43, 13 August 2012 (UTC)

"A reflected rainbow will appear as a mirror image in the water surface". Isn't that misleading?

The rainbow is not a physical object and cannot be reflected as in a mirror. The reflected rainbow is a different rainbow, not an image of the one in the sky. (78.150.192.55 (talk) 19:20, 23 July 2012 (UTC))

That sentence is not misleading because many people experience the rainbow as a celestial projection. The celestial projection of the reflected rainbow is the mirror image of the rainbow. For example, take a look at the rainbow images at http://apod.nasa.gov/apod/ap070912.html. Those arcs look like celestial projections. Ceinturion (talk) 21:50, 23 July 2012 (UTC)

It is precisely because the reflected rainbow may look like a mirror image of the rainbow in the sky, that the sentence is misleading. The reflected rainbow is an image of the rainbow that would be seen by an observer located where the light rays are reflected from the water surface. A diagram would help. Other websites give satisfactory explanations. (78.151.36.249 (talk) 12:52, 25 July 2012 (UTC))

It is just a play of words. One might ask: is it possible for two observers to see the "same" rainbow? Some might say no, because the observers "see" different raindrops. Others might say yes, because they see the same celestial projection. In my opinion this play of words is funny, but distracting from the essence. (Btw, referring to unspecified "other websites" is a poor source.) Ceinturion (talk) 13:50, 26 July 2012 (UTC)

I am not trying to be funny or pedantic. If an observer were to see a reflected rainbow when he could see no rainbow in the sky to be reflected, he might seek an explanation from this article. I believe he would be confused by the sentence in question.(78.150.203.117 (talk) 15:40, 26 July 2012 (UTC))

I don't agree with Woodstone's edit: The reflected rainbow is not a mirror image of the primary rainbow, since the crest of its mirror image is displaced by twice the height of the observer above the water table (diff). The horizon is always the mirror axis between the rainbow circle C and the reflected rainbow circle C'. Evidently, the pot-of-gold-line (the intersection of the rain curtain and the water surface) is not the mirror axis, because that line is at height h below the horizon, where h is the height of the observer above the water surface.) Ceinturion (talk) 09:40, 6 August 2012 (UTC)

This explanation by Ceinturion states the facts correctly. However I contend that the rainbow is not perceived as infinity far, because how could one then imagine a pot of gold at its end? The rainbow appears clearly in front of all scenery and with careful observation, even a faint rainbow can be seen right in front of the observer. Physically also, there is no light from the primary rainbow that reflects in the water to reach the observer. −Woodstone (talk) 11:54, 6 August 2012 (UTC)

For example, if a primary rainbow crosses a tall building at a certain floor, the reflected rainbow would cross the reflected building at a lower floor. −Woodstone (talk) 15:38, 6 August 2012 (UTC)

I think in science the rainbow is more often said to be infinitely far away, because of the parallax. For example in the book The Rainbow Bridge: Rainbows in Art, Myth, and Science by Lee (2001): the rainbow has no particular position in space, unless that position is infinity. .. You cannot claim that the bow is, say, one yard away, even if it is caused by a water sprinkler that you hold in your hand. ... You can check on this by taking a stereoscopic picture of a bow seen in the spray from a garden hose. The rainbow appears infinitely far away, having seemingly punched its way right through foreground objects in its headlong run to recede from you. Do you have a reference that says the rainbow is inside the rain curtain, or is it your personal point of view? (Btw, a virtual object can be located behind scenery, even behind a solid wall. That happens, for example, when we look in the mirror.) Ceinturion (talk) 21:33, 6 August 2012 (UTC)

Yes, in the end the rainbow is a reflection of the Sun, and as such the virtual image is much farther away than the scenery. But take a picture of a rainbow and reflected rainbow in the landscape. Print it on a transparent sheet, cut it in half, flip one over and try to match the images. You will not succeed. So it would be confusing to state that the reflected rainbow is a mirror image. −Woodstone (talk) 09:26, 7 August 2012 (UTC)

On the pictures that I tried (for example the one at the right, and [1], [2]) the rainbow circle C and the reflected rainbow circle C' are matching fine as mirror images with respect to the horizon. Please provide a picture where they don't match. Surely this whole discussion is just a play of words. Ceinturion (talk) 11:53, 7 August 2012 (UTC)

Please have a look at this picture. On the left side, the red band of the primary rainbow passes over the tree. The reflection rainbow passes through the tree. So the picture as a whole is not a mirror image. −Woodstone (talk) 14:44, 7 August 2012 (UTC)

Actually, your picture confirms that the rainbow is very far away. See [3]: the red line is the mirror axis of the tree (height h below the horizon). The green line is the mirror axis of the remote mountains. The mirror axis of the rainbow coincides with the green line. Ceinturion (talk) 17:07, 7 August 2012 (UTC)

Back to cutting the picture in half. There is no place to cut so the halves match. To match the tree, you must cut along the red line, to match the rainbow you must cut along the green line. In a 2-D picture made from physical light as e.g. on a retina, there is no symmetry. In the 3-D world and assuming a virtual infinitely far rainbow there is. What is a more observable truth? −Woodstone (talk) 21:28, 7 August 2012 (UTC)

I'm lost. I don't understand your reply and question. I think you are commenting on using the mirror axis of an object in the water as a visual cue to estimate the distance of the object (which would be uncontroversial in a rainbowless picture like [4]). I suppose you mean that that estimate is not a fact. Although it quacks like a duck, it doesn't have to be a duck. Right. But in my opinion it is more informative to say that it quacks like a duck than to say that it is not a duck. Ceinturion (talk) 10:40, 8 August 2012 (UTC)

This is a bit of a strange discussion. If you look onto the surface of a lake and see an upside down rainbow, who wouldn't call that a mirror image? It is created through reflection in the surface. Things often don't look the same in a mirror since that gives a different perspective. Ulflund (talk) 13:49, 9 August 2012 (UTC)

I agree with the revised wording, but I still think a diagram would help and remove the need for the complicated argument that has developed. The reflected rainbow is indeed a mirror image, but not a mirror image of the one that may or may not be visible in the sky.(2.96.70.225 (talk) 16:01, 9 August 2012 (UTC))

I re-removed the statement that the reflected rainbow is not a mirror image, because no adequate explanation has been given here. The statement depends on the assumption that the rainbow is located inside the rain drops, whereas the parallel rays that reach the eyes (or the camera lens) imply an infinitely remote virtual object, according to optical geometry. Neither the scenery nor the location of the water drops brings the virtual object any closer. Ceinturion (talk) 19:18, 13 August 2012 (UTC)

"When a rainbow appears above a body of water ..." implies that a reflected rainbow can be seen only when the observer can see a primary rainbow in the sky.(89.240.176.211 (talk) 20:43, 18 August 2012 (UTC))

Reflection rainbow / twinned rainbow

The reflection rainbow section needs to be redone. What is called a "reflection rainbow" (not "reflected rainbow") in this section (and the explanation which was taken from the photo) is actually a "twinned rainbow". If one reads the ref for twinned rainbow, one learns that it offers the first explanation for this rare rainbow. I'm going to make the changes. Gandydancer (talk) 20:25, 9 August 2012 (UTC)

Well, in all the time I've been here at WP I don't think I've ever been more embarrassed and frustrated with my editing! After a great deal of reading and believing that I was updating info here to reflect the new info from the twinned rainbow site I ran across a site that includes both twinned and reflection rainbows. I hope I've undone any damage I did but will go through my changes again when I am done pulling my hair out. I hope not to be judged by this mistake--I'm usually pretty careful and don't jump to conclusions... (grrrrr) Gandydancer (talk) 22:01, 9 August 2012 (UTC)

Isn't this new 'twinned rainbow' section positioned too high in the variations list and too enthousiastic?[5] The existence of twinned rainbows is not well established (for example, the Atoptics website is fairly prudent) and they are rarely observed. Your enthousiasm seems to be based upon a recent numerical simulation by the Disney team. However, the current section suggests that they did not perform any real measurements of the rain drop shapes and sizes. In that case it remains an educated guess like before, instead of "the explanation". Ceinturion (talk) 23:45, 16 August 2012 (UTC)

Sorry, I missed your post till now. I think you make a very good point and it has bothered me as well. For one thing, I have seen more than once "overly enthusiastic" press releases re other studies that have been done. The researchers want to get attention--and probably more research money as well. What do you think we should do--or go ahead and fix my edit if you have a good idea about how to go about it. Gandydancer (talk) 20:58, 18 August 2012 (UTC)

Dispersion Diagram

It's actually a flattened drop of water due to the upward resistance. I would present it as more of a pancake shape with an elliptic cross section. This shape more clearly demonstraits the white wash observed above and below the horizontal position of the backlight. — Preceding unsigned comment added by 70.185.221.179 (talk) 00:52, 15 August 2012 (UTC)

It is unclear which section or figure you are discussing, and which whitewash you want to demonstrate. Google reports no hits for whitewash + rainbow. If your post is an opinion, discuss it in a meteorology forum. If it is a fact, provide a reference and rephrase. Ceinturion (talk) 13:56, 15 August 2012 (UTC)

Sources from Optics InfoBase

Would it be possible for someone from Wikipedia to create a/some page(s) about the sources from Optics InfoBase (e.g. 14, 15) as it cost $15 or $35 depending on whether you are a member or not.

Many Thanks

ThomasRules 19:57, 13 November 2012 (UTC)

Diagram Disagrees with Photographic Reality

In all the photos, when the sun is behind the photographer the inside of the primary rainbow is blue and the outside is red. In the little refraction diagram, which appears to show a drop on the upper part of a rainbow, the colors are reversed. You should fix this so it reflects (no pun intended) the reality of the photographs. — Preceding unsigned comment added by 2001:558:6020:13B:7820:6E5C:D4A1:28DE (talk) 07:16, 28 November 2012 (UTC)

The diagram is correct. You will see the different colors in different rain drops. Red is the lowest (largest angle) in that figure, and the uppermost color in the rainbow (also largest angle) as it should be. Ulflund (talk) 17:11, 28 November 2012 (UTC)

I get it now! The blue and red come out at different angles, at diverging paths. So it is impossible for a single person to see red and blue from the SAME exact water drop. That was the mistake I had made. Blue comes from one set of drops, and red from another. The blue beams are at a shallower angle (more toward the horizontal plane of the Earth's surface) than red beams, so the blue I see must be below the red I see (when looking at the top of the rainbow). This effect is repeated in a circular pattern and I see a blue ring inside red. Thanks for the clarification! So cool! — Preceding unsigned comment added by 146.142.1.10 (talk) 19:37, 28 November 2012 (UTC)

The diagram at the right (from an earlier version of the article) exaggerates the divergence of the reflected red and blue rays. Hence it might be slightly easier to understand. Ceinturion (talk) 01:10, 29 November 2012 (UTC)

Typo, can someone fix it?

Someone spelled maneuver wrong in the overview section. They spelled it manoeuvre. It's a simple fix, but the article is semi-protected (not sure why) so i cant do it myself. --The Great and Powerful Qbr12 (talk) 19:46, 24 December 2012 (UTC)

• It is done...oh Great and Powerful one...

Thanks for catching it. Happy Holidays....Pocketthis (talk) 00:23, 25 December 2012 (UTC)

I've reverted as the previous spelling was correct: http://oxforddictionaries.com/definition/english/manoeuvre Variations of English should be consistent in articles. Thanks. Zarcadia (talk) 19:43, 1 January 2013 (UTC)

• I've never seen it spelled that way. Learn something new every day..;) It would appear from the link you provided that the way I was spelling it was the USA way to spell it. Logically, since this is an International Site, you're OK with spelling it old school. However, Webster disagrees with you:
• ma·neu·ver

noun \mə-ˈnü-vər, -ˈnyü-\ 1 a : a military or naval movement b : an armed forces training exercise; especially : an extended and large-scale training exercise involving military and naval units separately or in combination —often used in plural".

• I'll leave your edit the way it is and leave it to greater minds to decide. However, I would venture to say that 'Maneuver' is the modern, and more widely used way to spell the word, and most folks from wherever they're from will get cross eyed seeing spelled your way. :) Pocketthis (talk) 20:24, 1 January 2013 (UTC)

Monochrome rainbow

How reliable is the photo and description of the rare monochrome rainbow, which was added to the article by Astronautilus on 16 februari 2011? My impression is that it is an artificial image, taken through a red filter. A quick search on internet did not provide similar images. In addition, a quick search on internet did not provide a reference for the existence of this category of rainbow. Is it original research? Ceinturion (talk) 11:06, 29 November 2012 (UTC)

It does seem to happen at times--see the "red bows". [6]. BTW, that really is a great site. Gandydancer (talk) 14:34, 29 November 2012 (UTC)

The red rainbow photos on the Atoptics site are significantly different: the landscape and the grey clouds contain many color shades, and they immediately look natural. On two photos even the "red" rainbow contains other colors. By contrast, the sky (perhaps clouds) on the Astronautilus photo looks unrealistically monochrome. Ceinturion (talk) 22:26, 29 November 2012 (UTC)

Rainbow Sunset

He is a professional photographer. I guess you could ask him. If you look at this one from the Commons and imagine it cropped down to just the lower right or left it can somewhat match the one we are using. Gandydancer (talk) 04:16, 30 November 2012 (UTC)

I asked him. He assured me that the photo of the red rainbow is exactly as it was seen. Case closed. Ceinturion (talk) 00:32, 7 December 2012 (UTC)

"Primary" colours

Why does the article on the colours in the rainbow describe the seven traditional colours as "primary colours"? This term usually refers to the three colours used in mixing light or pigments, with colours such as orange being termed secondary colours. — 146.179.8.133 (talk) 11:33, 12 February 2013 (UTC)

The term "primary" colours was first introduced in the article in a single statement that Newton distinguished seven primary colours.[7] In that case it conformed to Newton's terminology.[8] As it is used in the current version of the article mostly unrelated to Newton, it might be better to replace it by a neutral term like "principal" colours. Elevant (talk) 16:04, 12 February 2013 (UTC)

I replaced primary by main colours. In addition, I removed the statement "Note that what Newton called blue .. [is] what we call cyan .. today". The statement is not very relevant for rainbows in the atmosphere, and it is already stated in the indigo article. The sentence formulation was a bit confusing, because elsewhere in Opticks Newton says: an excellent blue of a bright sky-colour.[9] I don't believe we would translate that as an excellent cyan of a bright sky-colour. Ceinturion (talk) 18:41, 12 February 2013 (UTC)

"Snowbows"

A "snowbow" is a phenomenon of the same nature as rainbow, but with a few differences: they have a steeper slope and appear to encircle the sun (a photo) — Preceding unsigned comment added by 85.181.224.88 (talk) 19:46, 15 March 2013 (UTC)

The sun is visible in its center and sun dogs on both sides, so it is a halo. Snowbow is a misnomer because it is caused by ice crystals, not by snow. Elevant (talk) 08:33, 16 March 2013 (UTC)

cultural significance

This article is missing the cultural significance of rainbows, their symoblism, use in legends and myths, etc. There should be a summary of those articles in that section, not just a bare sentence. -- 65.92.180.137 (talk) 23:04, 28 March 2013 (UTC)

The information is not missing. That single sentence, containing three links, is a better summary than many words. The information is just a click away. Ceinturion (talk) 08:52, 29 March 2013 (UTC)

Any volunteers?

Just when we think Wikipedia is finished another glaring hole pops up! While doing the above research I realized that we have not covered the reason that the sky inside of a rainbow is always brighter than the sky outside of it. Here is a good source to explain it: [10]. Anyone care to tackle it? If not I will when I have time--I'm working on something else right now. Gandydancer (talk) 13:25, 18 April 2013 (UTC) I put it in the article and hope it is OK. Gandydancer (talk) 15:38, 19 April 2013 (UTC)

Complete circle rainbow

I can't see where this would fit in the main article, but a rainbow appears (obviously, when you think about it) as a complete circle when viewed from an aircraft. I have seen this once, and it's spectacular! FCR 86.220.74.222 (talk) 10:36, 18 April 2013 (UTC)

Thanks for the delightful note! I added it-please edit as needed or perhaps it's OK as is. Gandydancer (talk) 12:29, 18 April 2013 (UTC)

I have seen a rainbow as a complete circle with the sun at its centre with the sun directly overhead. How can this be explained ? — Preceding unsigned comment added by 91.226.168.2 (talk) 07:03, 14 July 2013 (UTC)

Your phenomenon is a halo, not a rainbow. It is caused by reflection in ice crystals instead of water droplets. Ceinturion (talk) 19:22, 14 July 2013 (UTC)

Tertiary and quaternary

According to [11] prior to this search, there were only 5 scientific descriptions of tertiary rainbows in nature, over a period of 250 years. Now, there's photographic proof of tertiary and quaternary ones. It would be good to add photos of these if possible, and expand the section on higher order rainbows. (along with the science for them) -- 65.94.79.6 (talk) 09:01, 26 June 2013 (UTC)

Full circle rainbows

I have reverted a string of edits to this section. It is not correct to say that one can't see the full circle because there isn't one. While all rainbows are, in a sense, an illusion, they are full circles but the horizon blanks out the lower portion. Please discuss before again adding this information. Gandydancer (talk) 21:56, 3 October 2013 (UTC)

• The horizon does not block out the lower portion. There is no "lower portion". It only exists if you are in a view of perspective to allow the illusion to continue into a circle. I tried to make some sense of a terribly childishly written paragraph this morning, after I was tracking an edit on it from a non-registered user from my watch list. I'm not a rainbow expert, but from what I remembered from school, I knew the paragraph was nonsense, and poorly written. As far as the "You" and "We", I took them out this morning, but I see the article is back to saying: "The Earth gets in the way" again, and the wording is that of a child again. I agree with Escape_Orbit. A simple explanation of what it is, and when it's possible to see the phenomenon, written like a grown-up, and not a child. If I don't see that paragraph get fixed properly soon, I am going to "totally" rewrite it, and cite it. ThanksPocketthis (talk) 04:39, 4 October 2013 (UTC)

There are multiple problems with this paragraph. Specifically;

• The cite provided, http://www.weatherquesting.com/rainbow-circle.htm, doesn't lead to anything that supports this paragraph. So the section is entirely unsourced.
• The paragraph is written in American English. This article is in UK English. So spelling of "centered" should be changed.
• The paragraph makes more than one reference to "you" and "we". Wikipedia does not address the reader in the second person or refer to itself.
• "A rainbow is a circle of angular radius 42 degrees, centered on the antisolar point" - this is already far better explained above in the Rainbow#Explanation section.
• "we don't see the whole circle because the earth gets in the way" - What does "get in the way" mean? If we can't see a rainbow on the ground, it's not because the Earth "gets in the way" of it. It has no "way", it is an illusion. It simply can't be seen where there are no suitably lit raindrops to refract the light.
• The Earth is a proper noun and should be capitalised
• "only possible from an aircraft" - the rest of the paragraph immediately contradicts this misleading statement.

If you can't fix these problems, and explain what makes a "full circle rainbow" any different from any other rainbow already described, then it should be removed, or at the very least re-written. The only part I can see a justification for is an explanation of why a full circle can be seen when looking down from a height. The rest of it is confusing, already covered or incorrect. --Escape Orbit ^(Talk) 22:34, 3 October 2013 (UTC)

Actually, the rainbow can certainly be complete if it rains nearby, only the portion under the horizon will be much fainter. All droplets along the 42 degree cone contribute, regardless of their distance. Above the horizon, one can see far, so many drops are on the line of sight. below the horizon, one sees only drops that are closer than the intersection of the line of sight with the Earth's surface. −Woodstone (talk) 10:40, 4 October 2013 (UTC)

I have rewritten the section, however I have not left any of the details out as they are long-standing without any previous objections, and I believe that they are proper for the section. I hope I have fixed the issues mentioned, but please discuss problems that you may have with the section before again deleting information and hopefully we can work them out rather than edit warring. I'm aware that British English uses "centre" but was not sure how that would be changed to "centered"..."centred"? Gandydancer (talk) 11:22, 4 October 2013 (UTC)

• I'd like to stay out of this discussion, and I'll try, but not before leaving this note: I would like a science editor with not only the knowledge of the phenomenon, but the writing skills to explain it, so it sounds like someone with higher than a 5th grade education wrote it. No offense intended Mr. Gandydancer, but what you have written to explain a full circle rainbow, makes me feel embarrassed to be a Wikipedia editor when I read it. This is no time for egos. It's a time to explain this subject accurately and in Encyclopedic form or dump the section completely. Thanks. Pocketthis (talk) 14:23, 4 October 2013 (UTC)

I have reverted the following edit because Wikipedia is supposed to be written for readers with a general education and not only those with degrees in math. Most sites that discuss full-circle rainbows are easy to understand for the general reader and if they want to learn more the site used for (some) of this information may be useful. Here is the section that I am reverting to a more understandable version:

A rainbow looks like a circle of angular radius 42° centered on the antisolar point (the point marked by the shadow of the viewer's head), but actually it is formed by light reflected in water droplets located in a cone of angle 42° around the shadow line from the observer's eye. When the Sun is at elevation α, the bottom of the cone is at −α−42°. When the Sun is at 48°, the bottom of the cone is just at your feet (−90%deg;). When the Sun is higher than 48° the bottom of the cone is towards the Sun, and reflected light from the bottom will not reach the observer, and no full circle can be seen. When the Sun is lower than 48°, a full circle could be seen if droplets are present close by. The intensity of the colour is the cumulative effect of all droplets in the cone. The higher part of the cone will stretch far away and contain many droplets, especially if it is above the horizon. The lower part of the cone intersects the Earth's surface closer by, and fewer drops contribute, resulting in a faint colour. To see a full circle rainbow with intense colours, one must be able to look down on it, such as from an aircraft. Part of this edit is sourced, but even still, should Wikipedia expect the general reader to understand what, for instance, "−α−42°" might mean? Gandydancer (talk) 22:18, 5 October 2013 (UTC)

• First of all, as established editors, we don't "revert" each others edits, we edit what we think will improve what is already there or completely re-write it. Reverting is generally reserved for acts of Vandalism. On your first attempt to reinstate your childish paragraph, you actually reverted my changes "4 times" to achieve your original copy. How outrageously disrespectful of you. However, even after you did that, I did not reverse your version back to mine. In respect, I started over and re-wrote it. If you didn't understand −α−42°, you could have simply changed it to angular radius 42°. This is the excuse to revert the entire factual re-written paragraph by Woodstone? You have a lot to learn about editing on Wikipedia sir. Almost as much as you need to learn about writing an article that sounds like a grown-up wrote it. Mr. Woodstone: When and if you revert, or wish to re-write Gandy Dancer's cemented paragraph, get with me first, and we'll incorporate your knowledge and English style, with a more basic and simplified version of your facts. I'm pretty good at simplifying things.Pocketthis (talk) 03:08, 6 October 2013 (UTC)

I've had another go at fixing this. As previously noted, previously the section started with a confusing and unclear discussion of what was already explained in the article. And then when it finally got around to explaining "full circles" it wasn't much clearer. It also had a few grammatical errors. I've tried to re-word; probably not perfect, but I hope a improvement. --Escape Orbit ^(Talk) 18:34, 6 October 2013 (UTC)

• I like what's there now. It's a combination of info from all previous contributors, that is factual and easy to understand. Let's see how long it sticks..:) ThanksPocketthis (talk) 02:23, 7 October 2013 (UTC)

I have a lot of problems with it as written. I'll start with just one. Where do you both get that "While standing on flat ground this can only happen if the Sun is lower than 48° from the horizon, so that the line of sight stays in front of the observer." To see a rainbow the sun needs to be less than 43 degrees from the horizon, not 48. Gandydancer (talk) 04:24, 7 October 2013 (UTC)

Sorry, you can't just make stuff up. If no editor can present RS that states that the sun must be lower than 48 degrees rather than 43 degrees, I will delete that information from the article. Gandydancer (talk) 20:50, 7 October 2013 (UTC)

Please feel free to put whatever the correct degrees are. I didn't write any of the technical aspects of the paragraph. As long as a science editor (which I'm not) doesn't disagree with you, there should be no problems with changing that. However, just the technical aspects please. Please don't rewrite the wording, and don't revert anyone. Thanks. Pocketthis (talk) 21:16, 7 October 2013 (UTC)

I didn't get this figure from anywhere, I just reworded appropriately what was already there. If it's incorrect please feel free to fix it. --Escape Orbit ^(Talk) 21:52, 7 October 2013 (UTC)

What does this sentence mean?: Otherwise the amount of refracted light is insufficient to be visible, as it will be in the rainbow above the horizon. I've never seen it explained in this manner and don't know what to make of it. To my way of understanding the amount of light has nothing to do with it--it all depends on the angles between the sun and the viewer's eyes. Do you have RS? Also, you say above the horizon--all rainbows that are visable are above the horizon while those that are not visable are below the horizon. Gandydancer (talk) 13:22, 8 October 2013 (UTC)

As I said, I simply reworded as best I could what was already there. I understood this to mean that because the amount of water droplets visible along the line of sight below the horizon is limited (before you reach ground), the amount of light refracted is insufficient to be noticeable. Above the horizon, looking up into the sky, you don't have this restriction. This is why viewing from a high vantage point allows for more to be visible at a greater angle. Again, if you dispute this logic feel free to reword or remove (as I originally did). --Escape Orbit ^(Talk) 16:38, 8 October 2013 (UTC)

Thanks for your response but your understanding is not correct. Every raindrop is reflecting a full circle of light and if the "ground" (earth, horizon, etc.) was not "in the way" they would be a visible part of the rainbow (as they are from an airplane). It has nothing to do with the number of droplets. I have tried my best to explain this information and question the new information that has replaced what has been considered appropriate for some time now and have met with comments such as: ...it sounds like someone with higher than a 5th grade education wrote it. No offense intended Mr. Gandydancer, but what you have written to explain a full circle rainbow, makes me feel embarrassed to be a Wikipedia editor when I read it...outrageously disrespectful...You have a lot to learn about editing on Wikipedia sir. Almost as much as you need to learn about writing an article that sounds like a grown-up wrote it...On your first attempt to reinstate your childish paragraph...' I have searched for a better way to explain a full circle rainbow and can't find anything better than my last edit that was rewritten--which is so incorrect that I don't know where to start to fix it. I am an experienced editor and I frequently edit science articles and until now nobody has called me (as much as) stupid. I'm going to replace the present incorrect information with the version of a few days ago. If this results in an edit war I will ask for help from the WP science community. (BTW, I'm not a "Mr.") Gandydancer (talk) 04:35, 9 October 2013 (UTC)

Spectre

Last week someone changed the word 'fogbow' in 'fogbow spectre', in the legends of this image. (diff) Isn't that a mistake? I thought the Brocken spectre is someone's shadow at the center of a fogbow, and I would not mix those words. Could a native speaker of English have a look at it? Ceinturion (talk) 16:04, 9 October 2013 (UTC)

Thanks--I'll fix it. Gandydancer (talk) 19:04, 9 October 2013 (UTC)

Explaination of the rainbow angle

The direction of the sunlight is changed by the angle

$\theta _{1}-\theta _{2}=\theta _{1}-arcsin\left({\frac {sin(\theta _{1})}{n}}\right)$

twice, then the light is refracted entering or leaving a water droplet.

The direction is changed by

$\pi -2\,\theta _{2}=\pi -2\,arcsin\left({\frac {sin(\theta _{1})}{n}}\right)$

when the light is reflected once inside the droplet.

Total deflection after two refractions and k reflections in a water droplet therefore is

$2\left(\theta _{1}-(k+1)arcsin\left({\frac {sin(\theta _{1})}{n}}\right)\right)+k\pi$,

where $\theta _{1}$ is the angle of incidence and $\theta _{2}$ the angle of refraction and n the refractive index.

The condition

${\frac {d\delta (\theta _{1})}{d\theta _{1}}}=0$

means that the direction does not change varying the angle of incidence. This condition corresponds to maximum intensity.

From this condition we derive

$2\left(1-{\frac {cos(\theta _{1})}{n}}\,(k+1){\frac {1}{\sqrt {1-\left({\frac {sin(\theta _{1})}{n}}\right)^{2}}}}\right)=0$.

That can be transformed to

$\left({\frac {cos(\theta _{1})}{n}}\,(k+1)\right)^{2}=1-\left({\frac {sin(\theta _{1})}{n}}\right)^{2}$

and finally

$\theta _{1}=arcsin\left({\sqrt {\frac {(k+1)^{2}-n^{2}}{(k+1)^{2}-1}}}\right)$

In case of one reflection (k=1) in a water droplet that has a refractive index of about 1.33 the angle $\delta$ is about 180 - 42 degrees.

In case of two reflections the total angle change is 180° + 50,1°, in case of three reflections 360° - 42.8° and 360° + 42,3° in case of four reflections inside the droplet. 178.201.250.13 (talk) 23:01, 7 November 2013 (UTC)

Origins of the Rainbow

Our God mentions in the Holy Bible in the first chapter - Genesis Chapter 9 verses 11-17..... The first Rainbow (bow).

The Rainbow symbolizes God's promise to never flood the earth again.

Genesis 9:11-17

11 And I will establish my covenant with you; neither shall all flesh be cut off any more by the waters of a flood; neither shall there any more be a flood to destroy the earth.

12 And God said, This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations:

13 I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth.

14 And it shall come to pass, when I bring a cloud over the earth, that the bow shall be seen in the cloud:

15 And I will remember my covenant, which is between me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh.

16 And the bow shall be in the cloud; and I will look upon it, that I may remember the everlasting covenant between God and every living creature of all flesh that is upon the earth.

17 And God said unto Noah, This is the token of the covenant, which I have established between me and all flesh that is upon the earth.

Tothster (talk) 07:30, 24 November 2013 (UTC)

Not done: see your talk page. Callanecc (talk • contribs • logs) 12:18, 24 November 2013 (UTC)

The rainbow is a hologram

I have the idea that a rainbow is a hologram, that each droplet of water is a tiny rainbow and that together they reflect holographically the rainbow we see in the sky. I researched around and haven't found any mention of it. Any comments? Mappley (talk) 02:33, 23 November 2013 (UTC)

This Talk page is not a discussion forum for questions about rainbows. Please discuss your question in a physics forum like [12]. Ceinturion (talk) 17:56, 24 November 2013 (UTC)

Typo - possessive

Very high standards, but I couldn't help noticing a typo in the second paragraph - incorrect possessive:
"'the illuminated droplets above the horizon from the observers line of sight'" ("observers" is plural of "observer")
should be:
"'the illuminated droplets above the horizon from the observer's line of sight'" ("observer's" is intended meaning)
Phylasnier (talk) 12:53, 22 December 2013 (UTC)

Physics of rainbows and full circle

Light rays enter a raindrop from one direction (typically a straight line from the Sun), reflect off the back of the raindrop, and fan out as they leave the raindrop. The light leaving the rainbow is spread over a wide angle, with a maximum intensity at the angles 40.89–42°.

White light separates into different colours on entering the raindrop due to dispersion, causing red light to be refracted less than blue light.

Let's restart. Most of the relevant information is already present elsewhere in the article. Look at the copied pictures. The first shows that at a certain angle there is maximum reflection. The second shows that this angle depends slightly on the colour. So for ease of talking lets say, the maximum reflection for red is at 42° and the maximum for violet at 41°. The different colours from one drop reflect in different directions and do not reach the same observer. One observer sees red from drops in direction at 42° from the shadow of their head, and violet from other drops at 41° from the shadow. When the line of sight is above the horizon, one can see far and catch reflections from many drops, leading to clearly visible colours. More to the side and bottom of the rainbow, the line of sight touches the surface, and only drops up to that point contribute. In most cases, the lowest line of sight (to the bottom of the rainbow) will touch the ground at a few meters distance, so only very few drops contribute. If one is in the rain and looking carefully at a rainbow, one will almost always be able to see parts under the horizon. In bright Sun and fine dense rain, one will see the rainbow continue faintly till rather close by. The Earth is not in the way, but prevents raindrops to be present below the surface. −Woodstone (talk) 12:41, 9 October 2013 (UTC)

I've never seen RS that suggests that rainbows "touch the ground at a few meters distance...[but] only very few drops contribute" so that "one will see the rainbow continue faintly till rather close by." Can you provide a source? A new editor has entered with his/her wording--which I think works very well. Gandydancer (talk) 13:35, 9 October 2013 (UTC)

• How much did you pay him to go in and mention the garden hose again?.....lol. The garden hose is so dumb on so many levels, there isn't enough gig space to start explaining why it shouldn't be there. The scientific community can never agree on anything can they? It's 50% or more....ego. At least with the arts, the subject is subjective, everyone's opinion can be totally different, but still be appreciated. I'm glad I have a B.A. and not a B.S., because I'm beginning to see that B.S. can also mean BS...:) All kidding aside, I like the latest version by Vashti, except for the completely unnecessary garden hose info that's not really relevant here since the reader didn't come here to read about his Garden Hose experiences. I liked Woddstones the best, after it was simplified for the average mind. Also, GandyDancer has snuck in his version of a full circle rainbow above this paragraph anyway in the "Explanation" section. I'm surprised an admin didn't step in and just dump the paragraph completely. oops, guess what.......it's gone. Looks like Mr. Woodstone beat the admin to it. Can't wait to see the next exciting chapter of the: "Full Circle" by Alfred Hitchcock..:) Pocketthis (talk) 15:07, 9 October 2013 (UTC)

In 1637 Rene Descartes wrote, according to this:

"Considering that this bow appears not only in the sky, but also in the air near us, whenever there are drops of water illuminated by the sun, as we can see in certain fountains, I readily decided that it arose only from the way in which the rays of light act on these drops and pass from them to our eyes."

From "Physics of the air" by William Jackson Humphreys:

"Popular Questions About the Rainbow. — A few popular questions about the rainbow need perhaps to be answered. "What is the rainbow's distance? " In the sense of its proximate origin, the drops that produce it, it is nearby or far away, according to their respective distances, and thus extends from the closest to the farthest illuminated drops along the elements of the rainbow cone. Indeed, the rainbow may be regarded as consisting of coaxial, hollow conical beams of light of different colors seen edgewise from the vertex, and thus having great depth or extent in the line of sight."

−Woodstone (talk) 14:42, 9 October 2013 (UTC)

Wikipedia is not RS. You need to show RS that explains full circle rainbows that includes your information. Gandydancer (talk) 19:07, 9 October 2013 (UTC)

Both sources are not WP and show that (part of) a rainbow can be seen nearby. That implies immediately that a full circle can be seen. −Woodstone (talk) 09:15, 10 October 2013 (UTC)

Wikipedia sources are expected to show that our articles are backed by facts, not implications of facts. For you to argue that your version is correct because a site implies that it is correct is using OR to back your claim. The former version, however:

While a rainbow is by physical definition a circle, it usually appears as an arch because its lower arc is blocked by the horizon. The height of the sun when the rainbow appears determines how much of the circle can be seen - so as the sun approaches the horizon, more of the circle comes into view, whereas the higher the sun is in the sky, the smaller the arch of the rainbow becomes. A full circle rainbow can only be seen from above, as from an aircraft. While it's possible to look down at a garden hose spray and see a circle rainbow, the shadow of the person holding the hose will act as an artificial horizon, blocking the lower part of the circle.

is backed by numerous sources, including, for instance, The National Center for Atmospheric Research. Furthermore, it has been included in the article for about six months and viewed by thousands of readers without a complaint that it is not correct. I'd suggest that it be returned to the article rather than removed while you substantiate your version of the section. Gandydancer (talk) 14:46, 10 October 2013 (UTC)

• If you gentlemen "do" decide to replace the above paragraph, I will object to the Garden hose part of. There are two many variables. First who is to say, "anyone" is holding the hose. The hose could be suspended by a string from a tree. It's just out of place here. If you need to mention this type of illusion in the section, exchange it with the mist from a waterfall, or something that happens naturally in Nature. Isn't that what this article is all about? The beauty of Nature. Leave the garden hose for watering your lawn please. ThanksPocketthis (talk) 18:37, 10 October 2013 (UTC)

• I've been doing some research on Rainbows due to all the controversy here about Full circle Rainbows. The simplest explanation I've found is described by a PHD named Jeff Masters. He has a weather site: http://www.wunderground.com/blog/JeffMasters/the-360degree-rainbow. A little bit about him: Dr. Jeff Masters co-founded the Weather Underground in 1995 while working on his Ph.D.; he flew with the NOAA Hurricane Hunters from 1986-1990. On his site, he shows a full circle taken from a weather plane. Above the photo the caption reads: “A rainbow is not a half-circle, but a full circle, as this photo taken from NOAA's P-3 Orion weather research aircraft demonstrates. A rain shower beneath the aircraft allowed me to see the entire circle of the rainbow, although the 23-mm wide angle lens was not quite wide enough to capture the entire circle”. However, the most interesting part of this page is that his explanation of rainbows in general starts off with: "All rainbows are actually a full circle. You usually can't see the full circle, since half of the rainbow lies beneath the horizon, where it is not raining. After all, there is no weather underground. However, if one is in an airplane or overlooking a waterfall, the 360-degree rainbow can be seen." If our article started in this similar fashion, it would eliminate any need at all for a "Full Circle" section, because the reader would know that "all" rainbows are full circles right from the first sentence of the article. What I especially like about the paragraph, is that there is absolutely no technical jargon in it at all. It’s just a simple way to start the article, and then let the technical jargon follow it as it already does. My only objection to his opening statement is the fact that the other half of the rainbow lies beneath the horizon where it is not raining. Since the rainbow doesn't "exist" under the horizon, but the observer is only seeing the part from his perspective where it is raining. Other than that, opening the article in a similar fashion and better explained, should solve our dilemma here and put it to rest. Comments? Pocketthis (talk) 14:43, 13 October 2013 (UTC)

"since half of the rainbow lies beneath the horizon, where it is not raining" Is a blind alley. First of all, it may be raining there, it may not, you just can't see it. The world is in the way. In order to create the rainbow effect, the sunlight needs to pass through the rain on its way to your eyes. If the world gets in the way this obviously can't happen. You can't see a rainbow, or the absence of one, through the solid ground.

It's not much different to the old question "if a tree falls in a forest, and nobody is there to hear it, does it make a sound?" Depends how you define sound. It moves the air around just the same, but there are no eardrums to convert that vibration to sound. In the same way, if it's raining below the horizon, the raindrops will scatter the sunlight whether you can see it or not. The rainbow at that hidden point, for you, does not exist because your rainbow is created at your vantage point conforming to all those geometry rules above, and you can't see it at points which are obscured.

If the earth suddenly became transparent you might see it. Does that mean it was there all the time, but hidden? Or not there because you needed to see it to "make it" exist? I vote the latter, really, because for any rainbow you can only consider it from your vantage point.

Now for the fun, Devil's Advocate bit - Of course, that means the bits hidden from you behind trees and houses don't exist either, for you... But they might exist for a guy standing 10 feet away from you, or for you, if you walk over there... We all have our own personal rainbows, and they move around with us...

Confused yet? Shut your eyes. You just killed a rainbow...Begoon ^talk 17:15, 13 October 2013 (UTC)

• This has been my point from the start of this mess. However science editors will disagree with us. There are variations to the concept as well. For instance, if we are talking about a rainbow that is on the horizon from our vantage point standing on level Earth, then I do believe that someone looking down at the droplets from a plane at sufficient altitude, may be seeing those same droplets in a full circle. Here is where I have a problem with the horizon argument: I live in the high desert. I see rainbows frequently that run from one side of a mountain to another 30 miles apart.

The rainbow in this example has nothing to do with any horizons. So from my vantage point I only see the half circle, and for me "there is no rainbow below anything". The bottom half does not exist from my perspective. However, again, if someone were in a plane looking down at the same rainbow, he would see the full circle if the droplets were high enough. For him, the rainbow would begin at a higher altitude, and he would be able to see a full circle. I've been doing nothing but reading everything I can get my hands on about rainbows, and I'm pretty sure I finally understand the phenomenon, not so much technically, but certainly logically. However, my intention here was not to be a science editor, and suggest the correct way to explain it, but to suggest "Opening the Article with the fact that all rainbows are Full Circle Rainbows", and at least eliminate the need to have a "section" explaining it further down in the article. I'll be happy to let the science editors wrestle with each other's egos, until a compromise explanation is agreed upon. I'll even be happy to help simplify it, if asked to, when they finally agree on something here. Pocketthis (talk) 21:49, 13 October 2013 (UTC)

Still the same mistake. The rainbow does not go from mountain to mountain. It continues in front of the mountains (pretty obvious in the picture at the top of the article). And also below the horizon, between the observer an the point where his line of sight towards the rainbow touches the ground. The rainbow is not a circle, but a conical surface viewed from the top. Next time you see a rainbow observe carefully and notice the faint continuation till almost at your feet. −Woodstone (talk) 14:18, 14 October 2013 (UTC)

• Hello Mr. Woodstone, Yes, that photo at the opening is exactly what I see here in the High Desert. My question is: Since the rainbow is in the forefront of the mountains, what role does the Horizon play in the photo? From my vantage point, I'm only seeing the droplets illuminated from my low point of perspective. In order for the rainbow to appear at all, the droplets must be high enough to for an observer to see the full circle at some altitude. If I were to be lifted directly upwards by a helicopter, the illumination from the sun on the droplets would allow me to see the rainbow moving with me, and finally a full circle would appear, because the rainbow is really just illuminated droplets. So, I have a problem with the Horizon in that situation. There are no droplets below the horizon, so there is actually no rainbow from my view of sight under that horizon. I'm not being difficult, I'm just tying to pry enough info out of your knowledge to understand this well enough to perhaps eventually have a consensus that allows us to write an opening paragraph that makes sense to all who read it. If I'm correct here in my explanation, then all rainbows ARE full circles, and rather than saying anything gets in the way, or droplets below the horizon to confuse the issue beyond the reader's comprehension, it's just a simple matter of perspective of the viewer whether or not the full circle can be observed. Thanks for your reply, as always. Pocketthis (talk) 15:38, 14 October 2013 (UTC)

The horizon itself has no effect on the rainbow. The only effect is when the line of sight at 42° from the anti-solar point hits the Earth's surface. Turning the view from the top of the rainbow, always keeping at 42°, from the centreline, at some angle, the line of sight will hit the ground. (If the observer is standing on the ground in a fully flat terrain, this would be on the horizon.) Continuing around the rainbow this touch-point will move quickly nearer by. So fewer and fewer drops will be between the observer and the end of the line of sight. If you are lifted up by a helicopter, these lines will become longer and longer and more drops add in the reflection. So there is no sudden point where one can see a full circle, just parts of the circle are usually very faint and not noticed by a casual observer. Try to imagine the conical surface where the drops can contribute. Its top is in your eye, its centreline along your shadow, its opening angle is 42°. −16:12, 14 October 2013 (UTC)

• OK, I actually think I get most of that, except for the point about the helicopter not getting me high enough to see the full circle. I would have expected you to say that the higher I was lifted, gradually, the more of the circle I would be able to see, until I was finally high enough to see an entire circle. The words "sudden point" never crossed my mind, and I wasn't implying that. Here's the big question however: Is Dr. Masters "incorrect" when he states that "All Rainbows are Full Circles"? If he is incorrect, then I'm going to take a break here, and let you guys fight it out. However, if he is correct, how would you explain it without the words: 42 degrees, horizon, anti-solar point..etc? The idea is to mention (if they are) that all rainbows are full circles in the opening paragraph, and let the technical jargon lower in the article be there for the reader/readers, depending on their IQ level, to absorb what they can of it. I feel certain after all of my research, that you will agree with Dr. Masters. If so, Is this a correct sentence: "All Rainbows are full circles, though the average observer only sees approximately the upper half of the circle". If we can agree on that much, we are on our way to an opening paragraph. Thanks again. Pocketthis (talk) 16:46, 14 October 2013 (UTC)

Indeed, supposing it is raining everywhere, every rainbow extends over a full circle. It is however not really a circle, but a cone (see quote from Humphreys above) viewed from the top, looking like a circle. the lower parts are usually fainter than the upper part and are often not noticed. The very bottom may be obscured by the shadow of your legs (that's where the airplane comes in). Can you work with that? −Woodstone (talk) 11:29, 15 October 2013 (UTC)

Obscured by the shadow your legs? If Humphrey did say something to that effect, his work is almost a hundred years old and I would hope that we would find something a little more recent. We have quite a few sources and they all refer to a circle, not a cone. While a cone is used in a diagram for illustration of the angles needed by/created by a ray of light for a rainbow to appear, no sources refer to an actual cone of light. See here for example:

[13] Gandydancer (talk) 13:53, 15 October 2013 (UTC)

Incidently, this illustration also works quite well to illustrate what I believe to be the best wording: While a rainbow is by physical definition a circle, it usually appears as an arch because its lower arc is blocked by the horizon. The height of the sun when the rainbow appears determines how much of the circle can be seen - so as the sun approaches the horizon, more of the circle comes into view, whereas the higher the sun is in the sky, the smaller the arch of the rainbow becomes. Looking at the illustration one can imagine the sun higher or lower and the amount of the bow increasing or decreasing as a result. One can also imagine the lower portions of the bow, the lower circle of the bow, out of sight below the horizon. Gandydancer (talk) 14:11, 15 October 2013 (UTC)

• OK. After reading both of your replies, it seems we agree they are all full circles, however, you guys disagree on some technical aspects of its shape. How about we open the article with this: All Rainbows are full circles, however, the average observer only sees approximately the upper half of the arc: 'the illuminated droplets above the horizon from the observers line of sight'.(end quote). This sentence only mentions those droplets "above" the horizon, and doesn't get involved with technical explanations of what may or may not be below the horizon, or at what altitude one may have to be at to see it. That can be explained lower in the article anyway you fellows decide to finally agree to some consensus on. Opening the article with this sentence will eliminate any need for a special section on full circle rainbows. The section shouldn't exist at all, if all rainbows are full circles, and I think we have all agreed on that. Replies? If I don't get any objection to opening the article this way in 24 hours, I will rearrange the opening with that sentence. ThanksPocketthis (talk) 17:00, 15 October 2013 (UTC)

If you want to change the definition in the lead you should open a new section for discussion--this one is about the full circle rainbow section. And no, I do not agree that to mention "full circle" elsewhere covers a Full circle section and it would be best deleted all-together. Like a monochromatic rainbow or any of the other seldom-seen types, it deserves its own section. Gandydancer (talk) 00:08, 16 October 2013 (UTC)

• If all Rainbows are full circles, then the entire article is about them. Your logic is nonexistent. Also, we have been talking about the opening here long enough to justify the topic. You can argue with anyone you like about adding the Phantom section, that's your business. However. the sentence above alerts the reader from the opening, to better understand what he is reading below it. As far as a special section is concerned, perhaps one that says: "Seeing a Full Circle Rainbow" would be logical, if you care to write it.-Pocketthis (talk) 00:31, 16 October 2013 (UTC)

Woodstone has had a week to provide RS for his version and s/he has not done so. I have replaced the section--it is well-sourced and carefully written to reflect the information. I did not include the garden hose info per the statement that it would be deleted and this warring has gone on long enough. Gandydancer (talk) 01:22, 16 October 2013 (UTC)

I provided some very fundamental references above. If you want newer ones see for example:

• Finding and Photographing Rainbows
• The physics of rainbows
• The Rainbow
• Why does a rainbow curve down

−Woodstone (talk) 10:49, 16 October 2013 (UTC)

@Pocketthis--I thought that you meant that you wanted to change the definition. I think that your addition to the lead with the full-circle information is a good idea. Gandydancer (talk) 14:14, 16 October 2013 (UTC)

• I gave you the entire sentence I put in there today, so I'm surprised you misunderstood me. Yes, it fits in where it is like a glove. I like it too. And so ...the talk section settles another conflict. That's what it was designed for. Thanks-Pocketthis (talk) 14:25, 16 October 2013 (UTC)

• P.S. I also like the redesigned Full Circle Section you wrote. It's easy to understand, well written, factual, and considering that you have the technical explanations above it in "explanations", it works out quite nicely for the reader. Good Job. Thanks-Pocketthis (talk) 15:06, 16 October 2013 (UTC)

I misunderstood because you said, "How about we open the article with this: All Rainbows are full circles, however, the average observer only sees approximately the upper half of the arc: 'the illuminated droplets above the horizon from the observers line of sight'.(end quote)." ...so I thought you meant to use it as the opening sentence. However, I was surprised to find that it actually never was covered in the lead and I felt that your suggestion was excellent and planned to say as much in any further talk. Good Job! to you as well. :) Gandydancer (talk) 15:13, 16 October 2013 (UTC)

I'm sorry I'm a bit late into this discussion, but I have to say that you came to the wrong conclusion. From an airplane a rainbow can be a full circle as is described in the Variants section, but normally the rainbow is just a part of a circle. Saying "all rainbows are circles" is like saying "the moon is always full". It would be true if you where allowed to change your perspective (go high into the sky or out into space, respectively), but allowing that would make the original statement meaningless since it would also change the phenomena you are talking about. A rainbow is an optical phenomena, so it is what you see. If it that looks like half a circle it is half a circle. I suggest we remove the second paragraph of the lead starting with "All rainbows are full circles" since you need a quite odd definition of the rainbow to make it true and the only reference is a blog post. Ulflund (talk) 15:35, 2 January 2014 (UTC)

Good point and I agree. What do you think about this way to fix the wording. It now reads, "All rainbows are full circles, however, the average observer only sees approximately the upper half of the arc, the illuminated droplets above the horizon from the observer's line of sight.[1]" We could change it to read:

All rainbows have the potential to be seen as full circles, however, the average observer only sees approximately the upper half of the arc, the illuminated droplets above the horizon from the observer's line of sight.[1]

The fact that one may rarely view a full circle rainbow when looking deep down into a gorge shows that it is the "same" rainbow that would have seen as a semicircle if the steep drop off were not in existence. Gandydancer (talk) 16:21, 2 January 2014 (UTC)

You will not see a full circle when looking into a gorge since the ground you are standing on will block the sunlight for about half the circle. You need to fly to see it. Full circle rainbows are rarely seen, so I think they have gotten enough space already in the two places they are discussed further down in the article. Ulflund (talk) 16:38, 2 January 2014 (UTC)

• I just did an extensive research on Rainbows on over ten (10) reputable physics and science sites. Every single one, and every PHD says the same thing: "All Rainbows are full circles". They all mention the various reasons why we only usually see 1/2 of the arc, and seeing a full circle is difficult and rare, but they are all full circles none the less. You guys do whatever you like here. I won't object to any changes, however, I am going on record here that the way the sentence in the opening paragraphs read now is absolutely correct. Thanks-Pocketthis (talk) 18:22, 2 January 2014 (UTC)

If that is true I have no objection to the lead. Could you list at least a few of the sites where you found this? I would like to see how they came to that conclusion and insert a good reference in the lead. Ulflund (talk) 23:43, 2 January 2014 (UTC)

• • Here's two I especially liked because of the charts, and ease of the explanation.

http://wwwp.cord.edu/faculty/manning/physics215/studentpages/genamahlen.html http://science.howstuffworks.com/nature/climate-weather/storms/rainbow2.htm

The second of your sources, which I think is the more reputable one, says "If you were up above the rain, you would see the rainbow as a full circle", which is the point I have been trying to make. The first source I just think is wrong on this particular question. Until you show better sources I still think the paragraph should be removed. Ulflund (talk) 23:35, 3 January 2014 (UTC)

• • • Anyone can read both sources, and those and every other researched source agrees all rainbows are full circles. What's the difference if the only way you can see the full circle is from a plane? It's still a full circle just the same. You don't need me to research this. No one does. Google the question: "are all rainbows full circles", and you can read for three days on the subject, and the consensus is overwhelmingly "yes". Pocketthis (talk) 03:30, 4 January 2014 (UTC)

Pocketthis, the reason you think all sources say that "all rainbows are full circles" is because you interpret quotes like "If you were up above the rain, you would see the rainbow as a full circle" as "all rainbows are full circles". I know this because that is the only thing http://science.howstuffworks.com/nature/climate-weather/storms/rainbow2.htm says about full circles.

Googling for "are all rainbows full circles" will give you biased results since it will only show you pages that talk about rainbows as full circles, which most pages about rainbows do not. I still went through the list to prove my point and here are the top 10 hits:

1. Wikipedia doesn't count

2. [14] This one agrees with you: "We don't see a full circle because the earth gets in the way."

3. [15] I think this one agrees with me: "Can rainbows make a full-circle? If you could get up high enough in the sky, then you'd see that some rainbows continue below the horizon."

4. [16] is very similar to the previous one. "If you could get up high enough in the sky, then you'd see that some rainbows continue below the horizon."

5. [17] This one can be interpreted either way: "We usually don't see the full circle because the horizon of the Earth is in the way. The only way to see the full circle of a rainbow in the sky is to be above the raindrops and have the sun behind you. You would have to look down on the drops from an airplane."

6. [18] This one agrees with you: "Are rainbows actually circles without an end? Yes, but those circles are only observable from above under certain circumstances."

7. [19] This one is on my side: "If you were up above the rain, you would see the rainbow as a full circle"

8. Youtube doesn't count.

9. blacklisted:www.examiner.com/article/full-circle-rainbows Kind of gives us both right: "Full circle rainbows are normally only visable under certain conditions and perspectives." and "All rainbows are full circles, however the spray from a hose and the horizon while outside prevent the entire circle from being seen."

10. [20] is about sundogs which can be mistaken for full-circle rainbows (a special type of rainbow): "which has led to them being mistaken for full circle rainbows"

Googling instead for "Full circle rainbow" gives mostly hits that talk about the special case of rainbows where they form a cull circle. I agree that describing rainbows as full circles is common but it is even more common to describe them as bows or arcs. It still doesn't make the statement "all rainbows are full circles" true. Is Wikipedia supposed to help spread misconceptions just because they are already widely spread? Ulflund (talk) 16:22, 4 January 2014 (UTC)

• • • • I truly believe the only misconception is in your mind. I don't mean to be rude, but I just don't see a valid argument from you.The "Nature" of a Rainbow is a round object, illumination or refection. True, to see the entire illumination made by our round sun, you'd need to be in an aircraft to view it. I only have a Bachelor of Arts degree, however, I have done enough research, and read enough articles by PHDs on this subject, to feel confident I understand the phenomena pretty well. You yourself agree that they are full circles, but are rare to see, and an aircraft is a viable way to view them, so I don't understand why you're even here discussing changing a perfect sentence. "All rainbows are full circles, however, the average observer only sees approximately the upper half of the arc, the illuminated droplets above the horizon from the observer's line of sight". We have rehashed this for so long, and finally came to agreement, and then you show up months later arguing what? You agree that with enough altitude, the full circle can be seen. So if I was on the ground looking at the same rainbow, I would only see a portion of the arc. So what is your argument??? Since I'm not a science editor, I'll let you finish your "theory" with them. I'm exhausted ... you may win by default...:)-Pocketthis (talk) 19:01, 4 January 2014 (UTC)

I have expressed my opinion, but don't think the article should be changed without a new consensus. Sorry for taking so much of your time without getting anywhere. Ulflund (talk) 22:49, 4 January 2014 (UTC)

• Never be sorry for being polite and discussing your POV on a subject here. I'm the one who should be sorry for getting frustrated. I tried to read above and find a valid point in your argument, since you didn't seem to disagree with the fact that if I'm observing a rainbow from the ground and see a portion of the arc, and you were in a plane looking at the same rainbow, you might see the full circle because from your vantage point enough droplets are illuminated to show the entire circle. You make this point: "Saying all rainbows are circles" is like saying "the moon is always full". (end quote). When we speak of the moon, we speak of a solid object (mass). The phrase 'full moon' is just how much of the illuminated surface (by the Sun) we can observe from Earth. It's not a Phenomenon... it's a 'shadow'. From some perspective in outer space the moon 'is' always full. The difference is, a rainbow is a phenomena which in its nature or origin is round. Big difference between a Rainbow, and a shadow. So, if the best argument you have is the moon, then yes the article should stay just as it is. You can use a solar eclipse as an example since you used the moon. During a partial eclipse we only see a portion of the the Sun, however, the Sun is still there. Just because we can't see the full circle of a rainbow from the ground, doesn't mean the construction of the phenomena isn't round. The higher you get looking at a rainbow, the more of the arc you will see. All rainbows are full circles. How much you can see of it is just a matter of perspective. Is it fair for you to say something is "non-existent", just because "you" just don't happen to be in the right place to view it? Of course not. Thanks-Pocketthis (talk) 14:52, 5 January 2014 (UTC)

I'll try to explain my reasoning: The rainbow is an optical phenomenon, and is therefore only what you can see. There is no second half of the rainbow hiding behind the horizon that could make it a full circle. There are full circle rainbows visible from air planes, but as seen from the ground there is neither rain nor sunlight to produce the lower half of the circle. The lower half is therefore missing, not just hidden. A circle with a missing part is an arc of a circle, which is what I claim most rainbows are. I'm curious to hear what part of this argument you object to (if you still do).

About the analogy with the moon: It is a solid object, so even if it looks like a crescent it is really round. The moon crescent on the other hand is, like the rainbow, a sort of optical phenomenon, and can therefore make a half circle even though all parts are round. The main difference is between solid objects that have an objective shape independently of what we see and optical phenomena that are defined by what they look like. Ulflund (talk) 18:31, 10 January 2014 (UTC)

Please reread the quote given above (From "Physics of the air" by William Jackson Humphreys)

A few popular questions about the rainbow need perhaps to be answered. "What is the rainbow's distance? " In the sense of its proximate origin, the drops that produce it, it is nearby or far away, according to their respective distances, and thus extends from the closest to the farthest illuminated drops along the elements of the rainbow cone. Indeed, the rainbow may be regarded as consisting of coaxial, hollow conical beams of light of different colors seen edgewise from the vertex, and thus having great depth or extent in the line of sight.

The rainbow is not a circle but a cone seen from the top. Reflection in any drops, close or far, contribute to it. Between observer and points above the horizon there are many drops, so a strong colour. Between the observer and some point on the ground close by there are few drops, so the rainbow is very faint. There is a gradual decay of intensity with length of line of view. −Woodstone (talk) 14:01, 3 January 2014 (UTC)

So if you are standing in the rain and in the sun and had some kind of super vision you would see the full circle. But if it is not raining where you are or if you are standing in the shade (indoors for instance), the lower half will not only be weak, it will be nonexistent. Ulflund (talk) 14:56, 3 January 2014 (UTC)

Fully understood, if you interpret "lower half" loosely as "lower part". Similarly you might see a "quarter" circle if it's only raining to one side, or the sun is shaded by a mountain on one side. And supervision is not needed. Next time you see a rainbow look carefully and you will see it to a few meters from you on the ground. −Woodstone (talk) 16:26, 3 January 2014 (UTC)

Rainbows as mathematical functions

Newton discovered that white light can be split into rainbows, but ranbows can also be described as 3 sinus functions phase shifted from each other by 2/3 π.

If the sinus functions above are used as the combined color intensity of red, green, and blue we get the rainbow below.

Is it possible for this mathematical description of rainbows to be included in article? Zanthius (talk) 22:11, 18 January 2014 (UTC)

This is beyond my understanding. Do you have a ref? Gandydancer (talk) 23:11, 18 January 2014 (UTC)

Not except for from myself. I have been making rainbows on my computer for many years, but quite recently I figured out that a rainbow can be described very easily as 3 sinus functions phase shifed from each other 2/3 π.Zanthius (talk) 23:36, 18 January 2014 (UTC)

Spectral sensitivities (normalized responsivity spectra) of human cone cells, S, M, and L types

The reason you get something similar to a rainbow is because the sine functions you use are similar to the spectral sensitivity curves of the three types of cones in the human retina (see figure). There are differences, however. On a rainbow the outermost color is red, while with your method you get purple at that position. It certainly seems like a good method for quickly getting something that looks like a rainbow, but Wikipedia does not allow original research, so it does not fit here. A computer graphics forum is probably a better place to present your results. Ulflund (talk) 09:08, 19 January 2014 (UTC)

Actually the x value you put into the functions determines which outermost color you get. If the functions go all the way to 2π, then you get the same color you started with, which is purple. If however you only let the functions go to 3/2 π, then you get red as the outermost color. I understand however that this cannot be published at wikipedia, as you always need sources from non original research. It is a pitty however, because I think many people would find these functions helpful. Zanthius (talk) 19:31, 19 January 2014 (UTC)

Semi-protected edit request on 30 March 2014

In the section titled "overview" on the second line, reference is made to the "sun ray's". This is grammatically incorrect. Could I request that it be changed to the "sun's rays" 195.89.50.9 (talk) 13:22, 30 March 2014 (UTC)

This should not be changed. The sentence contains: "... viewed from a certain angle relative to the sun ray's", where at the end a repetition of the word "angle" is implied. −Woodstone (talk) 13:47, 30 March 2014 (UTC)

• Done I've fixed the grammatical error by replacing "sun ray's" with "light source" because the sun isn't required to make a rainbow anyways... — {{U|Technical 13}} ^{(t • e • c)} 15:15, 30 March 2014 (UTC)

Copyright problem removed

Prior content in this article duplicated one or more previously published sources. The material was copied from: here. Copied or closely paraphrased material has been rewritten or removed and must not be restored, unless it is duly released under a compatible license. (For more information, please see "using copyrighted works from others" if you are not the copyright holder of this material, or "donating copyrighted materials" if you are.) For legal reasons, we cannot accept copyrighted text or images borrowed from other web sites or published material; such additions will be deleted. Contributors may use copyrighted publications as a source of information, but not as a source of sentences or phrases. Accordingly, the material may be rewritten, but only if it does not infringe on the copyright of the original or plagiarize from that source. Please see our guideline on non-free text for how to properly implement limited quotations of copyrighted text. Wikipedia takes copyright violations very seriously, and persistent violators will be blocked from editing. While we appreciate contributions, we must require all contributors to understand and comply with these policies. Thank you. Diannaa (talk) 00:23, 29 April 2014 (UTC)

Footnotes to Rainbow page

External link to Footnote 9 is outdated. At present, it reads - Hutchison, Niels (2004). "Music For Measure: On the 300th Anniversary of Newton's Opticks". Colour Music. Retrieved 2006-08-11. & links to - http://home.vicnet.net.au/~colmusic/opticks3.htm The page has been relocated to - http://www.colourmusic.info/opticks3.htm Also, the link could well go to the start of the section about "Opticks", on the relation of spectral colours & musical notes - http://www.colourmusic.info/opticks1.htm

Another possible link from the "Colour Music" site would be - Hutchison, Niels. "Stairways to Heaven: Rainbow Enlightenment". Colour Music. http://www.colourmusic.info/rain.htm This is the first of 2 pages on the use/development of rainbows in art. It could well be used for the final paragraph, entitled "Culture". which begins - "Rainbows form a significant part of human culture. They occur frequently in mythology, and have been used in the arts."

Nielshutch (talk) 10:09, 1 May 2014 (UTC) Nielshutch (talk) 13:38, 10 May 2014 (UTC)

Re explanation

"The light at the back of the raindrop does not undergo total internal reflection, and some light does emerge from the back. However, light coming out the back of the raindrop does not create a rainbow between the observer and the sun because spectra emitted from the back of the raindrop do not have a maximum of intensity, as the other visible rainbows do, and thus the colours blend together rather than forming a rainbow"

Am I right in thinking that this needs to be edited?

...light coming out of the back of the rainbow...

...travels between the raindrop and infinity and so can never create a rainbow between the observer and the sun, not even the rainbow can do this because it is created between the observer and infinity ie the sun is behind the observer.

I think what the original text is getting at is that light travelling out of the back of the raindrop is diffuse and cannot create further rainbows beyond the point of maximum intensity which I think must be at 42° between the sun and the observer as it is reflected at the appropriate distance from the observer depending on the hight of the sun.

So maybe it should read "light coming out the back of the raindrop does not create a rainbow in relation to the observer and the sun..."

but then I'm not a scientist I'm a wiki reader so your thoughts please, --Indipage (talk) 20:03, 27 June 2014 (UTC)

What is meant by those sentences might be too complicated for Wikipedia. The diagram at the right might illustrate the word 'maximum'. Light rays may enter the water droplet anywhere between the center (eccentricity = 0) and the edge (eccentricity = 1). The diagram shows the exit angle after 0, 1, 2, and 3 internal reflections. The maxima of these curves correspond to (1) the primary rainbow at 42°, (2) the secundary rainbow at -50°, and (3) the tertiary rainbow at -137°. As curve 0 has no maximum, it does not generate a rainbow, merely 'zero order glow'. Ceinturion (talk) 18:00, 9 July 2014 (UTC)

Dispersion needs mention in the first line.

204.214.145.6 (talk) 22:42, 1 October 2014 (UTC) The word "Dispersion" should be included in the first line of the Article, along with Reflection and Refraction. First, there is the Refraction that occurs when light enters the drop. Next is the Dispersion of different wavelenghts (colours), as they get refracted at different angles. Then comes the Total Internal Reflection, and finally the refraction that occurs when light comes out of the drop. Hence, I would prefer to put Refraction, Dispersion and Reflection in that order. Raghavendra P Umarji 204.214.145.6 (talk) 22:42, 1 October 2014 (UTC)

Violet≠Purple --> MinutePhysics (youtube) video

i just stumbled across a video from MinutePhysics all about misconceptions over the colours in a rainbow. ≈Sensorsweep (talk) 02:05, 29 October 2014 (UTC)

Order of colors

The picture "White light separates into different colours" puzzles me. The red light is depicted there "on the bottom". If the picture were correct, the red color would lie in the inner part of a primary rainbow, but it lies in the outer part. Is the picture wrong? In any case this needs a clarification... — Preceding unsigned comment added by 70.114.197.37 (talk) 01:17, 3 November 2014 (UTC)

The figure is correct. The red light is directed more down than the blue, which means you will see it from water droplets that are higher up in the sky. I agree that the reason for this inversion in the order of the colors is not well explained in the article. Ulflund (talk) 19:44, 3 November 2014 (UTC)

Formula for the 42° angle

The todo-list at the holy top of this Talk page was added in 2007, and it has been ignored ever since. It is possible to add the formula for the angle, 4 arcsin(q/n) - 2 arcsin(q), where q = √((4-n²)/3), but formulas scare away readers. Or is it time to remove this item from the todo-list (or the entire todo-list)? Ceinturion (talk) 22:00, 2 September 2014 (UTC)

The explanation is actually not difficult. For a quantitative calculation we need the entire angle change as a function of incidence angle. Is the total angular change not dependent on the angle of incidence many rays are going in the same direction, that means the intensity is highest at that angle of incidence. 84.118.81.7 (talk) 18:25, 16 November 2014 (UTC)

If $\theta _{i}$ is the angle of incidence for refraction then the total change of direction to the incident beam after k reflections in the droplet is

$tot=2\left(\theta _{i}-asin(sin(\theta _{i})/n)\right)+k\,\left(\pi -2\,asin(sin(\theta _{i})/n)\right)$

The condition for maximum intensity is, that the total angular change tot does not depend on the angle of incidence $\theta _{i}$.

${\frac {d(tot)}{d\theta _{i}}}=2\,\left(1-{\frac {(k+1)\,cos(\theta _{i})}{n\,{\sqrt {1-\left(sin(\theta _{i})/n\right)^{2}}}}}\right)=0$

The sine function of the incident angle at maximum intensity is

$sin(\theta _{i})={\sqrt {\frac {\left(k+1\right)^{2}-n^{2}}{\left(k+1\right)^{2}-1}}}$ — Preceding unsigned comment added by 84.118.81.7 (talk) 15:33, 3 November 2014 (UTC)

Your statement that "q is the incident angle" should be "arcsin(q) is the incident angle" if you are using my q. Anyways, the intention of my comment was not to discuss lots of formulas. Ceinturion (talk) 20:08, 3 November 2014 (UTC)

Ok, I better choose $\theta _{i}=asin(q)$. With k = 1 it's your formular. It might be derived also from ${\frac {d(tot)}{dq}}=0$.84.118.81.7 (talk) 23:07, 3 November 2014 (UTC)

Right, my formula and your formula are identical for k=1, and they were derived in the same way. My formula, 4 arcsin(q/n) - 2 arcsin(q), equals 42° for n=1.333, and so does your formula for tot. Ceinturion (talk) 20:24, 16 November 2014 (UTC)