2006-09-25 04:52:48 · 8 answers · asked by Andy K 1 in Environment
The sky is blue partly because air scatters short-wavelength light in preference to longer wavelengths. Where the sunlight is nearly tangent to the Earth's surface, the light's path through the atmosphere is so long that much of the blue and even yellow light is scattered out, leaving the sun rays and the clouds it illuminates red, at sunrise and sunset.
Scattering and absorption are major causes of the attenuation of radiation by the atmosphere. Scattering varies as a function of the ratio of the particle diameter to the wavelength of the radiation. When this ratio is less than about one-tenth, Rayleigh scattering occurs in which the scattering coefficient varies inversely as the fourth power of the wavelength. At larger values of the ratio of particle diameter to wavelength, the scattering varies in a complex fashion described, for spherical particles, by the Mie theory; at a ratio of the order of 10, the laws of geometric optics begin to apply.
Individual gas molecules are too small to scatter light effectively. However, in a gas, the molecules move more or less independently of each-other, unlike in liquids and solids where the density is determined the molecule's sizes. So the densities of gases, such as pure air, are subject to statistical fluctuations. Significant fluctuations are much more common on a small scale. It is mainly these density fluctuations on a small (tens of nanometers) scale that cause the sky to be blue.
2006-09-26 02:53:41 · answer #1 · answered by Anonymous · 0⤊ 0⤋
(Sigh) Dude, go to ANY search engine and type this exact question and you will get a few million hits. The first few hits are usually the best. That is the purpose of search engines. You can get an answer in about 0.1 seconds instead of waiting for people who are no smarter than you to respond to your question.
2006-09-25 04:54:33 · answer #2 · answered by Anonymous · 2⤊ 1⤋
If I've answered this once I've answered it a thousand times, blue is the only color water vapor or ice will reflect.
2006-09-25 05:17:26 · answer #3 · answered by bprice215 5 · 1⤊ 0⤋
It's the colour of the junction of light and darkness..
2006-09-25 05:02:15 · answer #4 · answered by Drone 7 · 1⤊ 0⤋
how do you know blue is really a color someone told us that
2006-09-25 05:00:24 · answer #5 · answered by mike L 4 · 0⤊ 0⤋
NOT BLUE NOW HERE IN PARIS
2006-09-25 05:00:11 · answer #6 · answered by jean marc l 6 · 0⤊ 0⤋
because the grass is green??
2006-09-25 05:01:54 · answer #7 · answered by bdbarbie 6 · 0⤊ 0⤋
Is it? It's grey where I am!
2006-09-25 05:00:55 · answer #8 · answered by Bohemian 4 · 0⤊ 0⤋