12/30/2004: Green flash at sunset
http://cellar.org/2004/tenerifegreen.jpg
Credit and copyright Tony Cook and used with his permission. This was the Earth Sci pic of the Day a week ago. Taken on Tenerife in the Canary Islands, it's a great photo and also shows an interesting phenomenon - at the top of the sun, a green flash appears. This green is not on the sun itself, but a product of how the atmosphere affects the light. From the ESPoD explanation: Quote:
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very cool :thumbsup:
:3eye: |
pretty
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More pics of green flash.
http://www.polarimage.fi/sun2/ataulu2b.jpg I must say that this fella's website has the most incredible collection of sky / weather / water pictures. It was a BIG time sink for me when I came across it. Enjoy! |
On Golden Pond. :)
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I understand the color bit, but I wonder why the edges are so rough. Almost looks like an overexposure. Very beautiful to say the least. :thumbsup:
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Didn't we see a similar image a while back, I seem to remember something similar...
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I actually liked the last one that was used for IotD a bit better:
http://www.cellar.org/showthread.php?t=2395 This one is still pretty cool. |
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another note bene: this is also related to the reason sunsets are so pretty: the red and orange hues are caused by the lengthening of ths sun's rays as the sunlight travels further, it's in effect being stretched, and longer wavelengths are more red, while shorter ones are more blue. (this "redshifting" is an example of the doppler effect, which also explains why car engines sound higher pitched as they race towards you then suddenly lower as they recede) that's the gist anyway (from memory),someone else may post a more technically precise answer happy new year -cweekly ps I almost never post but I've lurked here for years. hi! |
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But the real answer to why you get the reds and oranges at sunset is the same reason the sky is blue. Go back and read the quote that Undertoad posted with the original picture again: Quote:
(I was going to explain why blue scatters and red doesn't, but I figured the more I write, the less people are going to take the time to read it) |
Thanks for the lessons, Guys. It does make sense, even to me. It seems like the sunrise & sunset would look almost alike, but sunrises are always loaded with yellows, golds, and oranges while sunsets are filled with reds and purples. A great gift nature has given us. I hope to enjoy thousands more at each end of the day. Imagine trying to explain how a beautiful sunset looks to a blind person who has never seen one. Now that would be a challenge..... ;)
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I wonder if the temperature of the air causes the sunrise/sunset color difference. In the morning, the sunlight is advancing through cold night air, and in the evening it is retreating through warmer daytime air.
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So how can we get green if the blue component in already dispersed? And how can the violet get dispersed if half of it is red yet the red doesn't? :confused: |
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Our eyes only see 3 colors: red, green, and blue. Using those 3 colors you can simulate most any color, which is why TVs and monitors only use red, green, and blue (RGB). There are 3 types of cone cells in your eyes, one for each of those colors, so every every color you see is based on the proportions that each of those cells are activated. When you see yellow, it means that both red and and green receptors in your eyes have been activated. Yellow light activates both red and green receptors (since its wavelength falls in between red and green), but if you mix red and green light, it has the same effect of activating red and green receptors. And when you see either yellow light or red and green lights mixed, you can't tell the difference, your brain just interprets it as yellow. On the absorbtion side of things, the primary colors are cyan (anti-red), magenta (anti-green), and yellow (anti-blue). That's why color printing uses Cyan, Magenta, Yellow and blacK (CMYK) instead of red, green, and blue to reproduce all the colors. Cyan absorbs Red light (and reflects green and blue), magenta absorbs green, and yellow absorbs blue, so they're the exact opposite of the 3 primary colors of light. If you take a picture on film, the negative will turn reds into cyans, magentas into greens, and blues into yellows. But when you mix paints, you aren't mixing pure red, pure yellow, and pure blue. It's hard to tell what light frequencies are being absorbed without using a spectroscope, so the exact colors you see when you mix two colors of paint all depends on which frequencies (colors) of light are being reflected and which cells in your eyes are being triggered by each frequency, and how strongly. It's not a simple subject at all, and I'm not going to attempt to explain any more here. Hopefully everything I've written here is understandable. If you want to know more, there's an excellent (and much more technical) explanation here: http://hypertextbook.com/physics/waves/color/ |
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