Wikipedia:Reference desk/Archives/Science/2023 August 5

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August 5

Thunder and the lightning

What is the physical explanation for the fact that thunder always follows lightning? AboutFace 22 (talk) 00:23, 5 August 2023 (UTC)

Light travels faster than sound. If you see the flash and hear the boom immediately, you're too close to it! ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:36, 5 August 2023 (UTC)

Lightning is a natural Electrostatic discharge in the atmosphere that heats gases in its path causing them to expand suddenly generating a Shock wave. A person at a distance perceives a flash of lightning almost immediately but onset of the sound of the shock cannot reach them faster than the Speed of sound which enables a simple estimate of the distance thus: count the seconds by which Thunder follows a lightning flash and divide them by 5 to get the distance in miles. More details and example thunder sounds are given at Thunder#Perception. Philvoids (talk) 02:37, 5 August 2023 (UTC)

Divide by 3 to get the distance in kilometres. HiLo48 (talk) 02:59, 5 August 2023 (UTC)

Thunder happens a split second after the lightning because the latter causes the former. The thunder is the sound of a rapid expansion of air caused by the super-hot lightning. The time taken between seeing the lightning and hearing the thunder increases with distance because, as already has been explained, light travels faster than sound. This article also explains how lightning is generated.[[1]] --Ykraps (talk) 07:10, 5 August 2023 (UTC)

A lightning in not a momentary phenomenon, the full discharge takes time. Given the heating of air happens at the beginning of the discharge, the sound start to propagate when the discharge still takes place. Zarnivop (talk) 12:37, 5 August 2023 (UTC)

When the shock wave is still forming the light has already begun to be emitted. The discharge takes about 50 milliseconds. Even if the shock wave begins to propagate instantly at Mach 10, by the time the discharge is over the front of the shock wave has travelled no further than say one fifth of a metre. It will then soon transform into a regular sound wave propagating at Mach 1. The last light emitted needs less than a nanosecond to overtake the shock wave. The light front has in the meantime travelled 15 km.  --Lambiam 14:56, 5 August 2023 (UTC)

Thunder caused by very distant or multiple lightning strikes is often heard as a reverberating rumble that is unsuitable for delay measurement. For distance estimating one needs to hear isolated thunder claps or thundercracks. The same arithmetic can be used to estimate a firearm's distance from its flash and sound. Philvoids (talk) 18:53, 5 August 2023 (UTC)

Don't forget that lightning has length. Even if we talk a thunder from a single lightning with no echoes, the thunder will rumble. In fact, you can calculate easily what is the distance from the point of lightning closest to you until furthest from you. Zarnivop (talk) 11:55, 6 August 2023 (UTC)

Occasionally one hears a sharp crack with a substantial delay after the lightning flash. I suppose this happens when the discharge channel, purely by chance, follows a course roughly along the surface of a virtual sphere centred on the observer's location.  --Lambiam 13:03, 7 August 2023 (UTC)

One of the main causes of thunder rumble is that the speed of sound varies significantly with air density, and since air is less dense further up, and lighting strikes are considerably long, the gap between the top of the bolt and the bottom of the bolt will be different; if the strike is close, the gap will be functionally small, so a sharp "crack" is heard, but the gap becomes greater with distance and so that crack gets "stretched out" into a rumble; there's also effects of reverb and echo as well. --Jayron32 16:11, 7 August 2023 (UTC)

Russia celebrates Radio Day to commemorate 7th May 1895 when Alexander Popov demonstrated his radio-based lightning detector. An audio recording of radio noise and thunder can serve as data for calculating accurately either the distance of lightning (assuming the speed of sound) or the speed of sound (assuming the distance). Philvoids (talk) 20:16, 7 August 2023 (UTC)

Taste range perception

Similarly to vision, hearing and smelling, where some animals excel humans, is it possible to have a taste range wider than the human one? I.e. sense also tastes that humans can't and have a wider taste perception of common food products? 212.180.235.46 (talk) 19:37, 5 August 2023 (UTC)

Sure. Taste tells us some rodents can taste starch (which humans cannot).  Card Zero  (talk) 19:44, 5 August 2023 (UTC)

Is it delicious to them? Sagittarian Milky Way (talk) 22:03, 5 August 2023 (UTC)

Tastes like chicken. HiLo48 (talk) 23:41, 5 August 2023 (UTC)

There was some research on the sense of taste in octopuses in October 2020. In this Wired article a scientist wonders "what is delicious to an octopus?". The question is confused by various factors: for creatures underwater, taste and smell are reversed (soluble particles float around while non-soluble ones stick to surfaces and must be touched to be sensed); an octopus tastes with its suckers; an octopus also thinks to some extent with its arms, raising deep questions about the locus of consciousness, and thus the meaning of experience, and making me hesitate to give any firm statement about anything.  Card Zero  (talk) 11:14, 6 August 2023 (UTC)

Some humans have greater ranges of taste than others.--User:Khajidha (talk) (contributions) 00:08, 7 August 2023 (UTC)

Indeed. See Supertaster. --Jayron32 13:12, 7 August 2023 (UTC)