Talk:Rainbow

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)

Snowbow

About the new section snowbow: Could this just be misstaken halos or fogbows? Either way it would be good to have a reference where the phenomenon in described either as how it occurs (what crystal shape is needed e.g.) or what it looks like (angle to the sun, width, color, preferably with an image). Ulflund (talk) 18:48, 27 January 2015 (UTC)

As the editor who added the new section.... "Snowbow" seems to cover a number of phenomena, certainly including halos, but some of the descriptions in the sources I found seem to describe something analogous to rainbows (i.e., arcs opposite to the sun's position). I'm still looking for more specific/technical references, and would appreciate some help! Dohn joe (talk) 19:14, 27 January 2015 (UTC)

This new section about the ill defined snowbow should be removed again because the author and the references all agree that it is not formed in raindrops. One of the references is by a meteorologist, Tom Skilling, who explicitly says that a 'snow bow' is formed in ice crystals (so it is a halo). The other two references, which suggest it is formed instead in 'snow crystals', are a travel guide and a dictionary. Last year someone posted a picture of a 'snow bow' on this talk page, which turned out to be an ordinary ice halo with sun dogs. [5] Ceinturion (talk) 00:30, 28 January 2015 (UTC)

I'd agree with Ceinturion here. Gandydancer (talk) 00:38, 28 January 2015 (UTC)

The question, though, is whether the phenomenon occurs opposite the sun, like a rainbow, as opposed to halos, which occur with the sun in the center. See also the discussion on my talkpage: User talk:Dohn joe#Snowbow. Dohn joe (talk) 01:26, 28 January 2015 (UTC)

Sure, feel free to investigate that question outside of this article. This article should contain solid knowledge about the rainbow, so I am going to remove the snowbow section now. Ceinturion (talk) 09:33, 4 February 2015 (UTC)

Thanks y'all for your contributions. It appears you are a knowledgeable bunch — would any of you care to look into my question regarding "true" vs. "false" moonbows here? Much appreciated! Drabkikker (talk) 15:16, 4 February 2015 (UTC)

You tube video of double rainbow

I removed the paragraph about a "viral video" on you tube that shows some guy's "ecstatic reaction to a double rainbow" but the edit has been reverted. What's the fact that some Z-list celebrity starts yelling and shouting about a common optical phenomenon got to do with an encyclopedia article about rainbows? I've seen lots of double rainbows and there is even a picture of one in the lead. It would appear from the article about the video clip (I despair!) that the reason it went viral was because "comedian and late-night talk show host Jimmy Kimmel linked to the video in a post on Twitter, saying that he and a friend had declared it the "funniest video in the world." The video quickly gained over one million views". So it was nothing to do with the fact that the video showed a double rainbow. The fact that millions of people are interested in watching this guy make an idiot of himself doesn't mean it belongs in what is supposed to be a serious informative article and it does nothing to further our knowledge of the subject. Richerman (talk) 18:47, 21 February 2015 (UTC)

I agree. That doesn't belong in this article. The reason the video went viral is not the rainbow. Ulflund (talk) 21:18, 21 February 2015 (UTC)

Seconded. I'll re-remove the section. Drabkikker (talk) 19:22, 27 February 2015 (UTC)

Removed confusing statement

I removed the statement "Others suggest that Newton in fact called indigo the colour now called blue, and blue the colour now called cyan" because it is a confusing paradox. Newton said the bright sky is an excellent blue. The statement would imply that today we say the sky is an excellent cyan. Which is nonsense. Surely the indigo article is a better place to discuss or explain the paradox. Ceinturion (talk) 00:44, 27 February 2015 (UTC)

Anaxagoras

Anaxagoras could be mentioned. — Preceding unsigned comment added by 195.16.110.189 (talk) 17:16, 7 March 2015 (UTC)

According to this the only surviving fragment from Anaxagoras that deals with the rainbow is "We call the reflection of the sun in the clouds the rainbow". That's not enough. Ceinturion (talk) 13:46, 8 March 2015 (UTC)

Colors of rainbow count

Is the colors of the rainbow is 6 colors: red, orange, yellow, green, blue and violet (purple)? — Preceding unsigned comment added by 72.244.200.161 (talk) 09:57, 9 March 2015 (UTC)

Color order in secondary rainbows

The article currently says "Secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and appear 10° outside of the primary rainbow at an angle of 50–53°. As a result of the second reflection, the colours of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside." This is incorrect. The number of reflections has nothing whatsoever to do with the order in which see the colors.

I've twice tried to correct it, with understandable text. Twice it has been reverted, with the claim that it was unintelligible. I suspect that it is because it contradicts commonly held, but incorrect, beliefs about how rainbows are formed. Specifically, So I'm going to try, once again. If you still think it is unintelligible, please tell me hear what it is you think is unclear so we can make it clearer to you. JeffJor (talk) 22:51, 25 April 2015 (UTC)