Talk:Rainbow

Rainbow = circle?

How can a rainbow be a circle? Can you provide any satellite pictures that can support this claim? Grinder 21:31, 12 March 2007 (EDT)

Visit Niagara Falls. When you are standing in (say) Victoria Park on the Canadian side on sunset, you up at the top of the falls, looking into a wall of mist that extends above and below you, and you see a whole circular rainbow in it. It's incredible. You can get calendars and postcards with pictures of circular rainbows in the souvenir shops.

Rainbows are huge circles around the "antisolar point." In late afternoon, the sun is behind you and above you, so if the "projection screen" of droplets only extends down to the ground, you only see less than half of a circle. To see a whole circle, you need to have a "screen" of droplets that extends above and below you.

From an airplane, if you're above cirrus clouds, you can often see much smaller rainbow-like auras surrounding the shadow of the airplane. In a novel called The War Lover by John Hersey, a bomber pilot flying in formation points out to his crew that there is an aura surrounding the shadow of their plane, but not any of the others. Of course, the crew in each of the other planes would have seen the aura appearing around the shadow of their own plane. Dpbsmith 15:25, 15 March 2007 (EDT)

Hey Grinder, here are some pics: Circular Rainbows Jrssr5 15:50, 13 March 2007 (EDT)

For a circular rainbow photo, how about http://www.mountainlight.com/gallery.aviation/images.html . If you wish to read about the physics behind the rainbow and other natural phenomena (twilight, alpenglow, green flash, twinkling stars, zodiacal light, secondary rainbows, tetrairay rainbows, alexander's dark band, etc...) Light and Color in Nature is a good book to read. --Mtur 15:35, 15 March 2007 (EDT)

"it has difficulty explaining why they seem beautiful and evoke such feelings of awe and mystery." ... has science ever tried to explain this? It comes off like a cheap dig.--Dave3172 12:08, 15 March 2007 (EDT)

How would you like to phrase it? I was trying for some compromise between various possibilities that occurred to me. I didn't want to say that science cannot explain the appearance of rainbows, because it can. But I didn't want to give the impression that science explains away rainbows. But it is possible that an evolutionist could hypothesis some adaptive advantage to perceiving beauty, so...

Ah, got it. Physics cannot explain...

If we just want to say rainbows are beautiful and awe-inspiring that's also fine, and if anyone want to slap a {{fact}} tag on it there shouldn't be much of a problem finding a source citation... like... hmmmm.... yeah, of course: Wordsworth, "My heart leaps up when I behold/A rainbow in the sky:/So was it when my life began;/So is it now I am a man;/So be it when I shall grow old, Or let me die!" I'll try making that change and see what people think. Dpbsmith 15:01, 15 March 2007 (EDT)

Colors that can't be reproduced

I have never heard of rainbows having colors that can't be reproduced. Is this poetic license, or fact? Kapntoad

Since that particular section doesn't have a citation I'm guessing it's mere opinion. --Cracker^talk 02:05, 16 March 2007 (EDT)

No, I didn't cite a source, but it's not opinion, it's fact. One example would be to try to reproduce it with RGB color, e.g. on a computer screen. On a CIE diagram, the three phosphors represent the three vertices of a triangle. All of the colors you can get by lighting up the three phosphors lie in the interior of that triangle. The colors of the spectrum, however, form a rounded shape well outside that triangle.

Colors made by mixing RGB are distinctly less pure and less saturated than real spectrum colors, especially in the parts of the spectrum that are "in between" the phosphors.

And a computer screen has a much larger gamut of color than a page printed with ink.

Color photographs look good, but if you have a chance to hold them up next to the actual thing that was photographed, anyone can see big differences from the real thing.

For another example, just try to photograph brightly-colored flowers in sunlight, especially those that have colors in the magenta-pink-violet-purple range. If you have a digital camera, take a picture, run inside, print it, and then bring it out to compare with the real thing. Not even close.

In other words... it's physics (and colorimetry and visual physiology),... not poetry or ideology.

Another problem, at least with ordinary printed pictures, is that halftone processes are at their very worst trying to produce a nice, smooth, even gradation of tone or color. A phenonemon called "banding" almost always occurs to some degree, in which tones that should grade evenly separate out into bands that have noticeable edges. So something like a spectrum, or a rainbow, or for that matter the gradual shading in any blue sky, are a severe test of printing quality. Dpbsmith 13:04, 16 March 2007 (EDT)

Backtracking...of course, I could be wrong... because it occurs to me that a rainbow, rather than a spectrum produced by a prism, might have enough blending to lie within a "Maxwell triangle..." No time to track this down. Similarly, some of the talk about "circular rainbows" above, including the images found in a Google search, are really a related but different phenomenon properly called a "glory." The circular rainbow at Niagara Falls is real, though I've been going nuts trying to find a photograph. Dpbsmith 13:10, 16 March 2007 (EDT)

Un, excuse me..

Um, the whole beginning of the article is completly opinion (albeit biblical opinion). This article as it stands is an embarassment and should be completely rewritten.Palmd001 17:09, 22 March 2007 (EDT)