kookaburra
Sunday, December 10, 2006
Why the Sky Is Blue
by John Ciardi
I don't suppose you happen to knowWhy the sky is blue? It's because the snowTakes out the white. That leaves it cleanFor the trees and grass to take out the green.Then pears and bananas start to mellow,And bit by bit they take out the yellow.The sunsets, of course, take out the redAnd pour it into the ocean bedOr behind the mountains in the west.You take all that out and the restCouldn't be anything else but blue.Look for yourself. You can see it's true.
Why is the Sky Blue: A simple Explanation
The sky is blue for the same reason that everything that is blue looks blue, like blue ink or a blue shirt. You may think that air, the main sky / atmosphere component, is transparent but thick layers of air - a few kilometers or miles, like the atmosphere's width, are bluish due to small dust perticles. So the sunlight that passes the atmosphere air reaches your eyes blue like a beam of bright like passing some blue glass or filter.
But why are sunsets and sunrises red? Because at sunset times the atmosphere air is red? To understand this you may need some more advanced explanation described in the following chapter.
Science:Why is the Sky Blue
Spectrum of blue sky clearly showing solar Fraunhofer lines and atmospheric water absorption band.
Diffuse sky radiation is solar radiation reaching the earth's surface after having been scattered from the direct solar beam by molecules or suspensoids in the atmosphere. Also called skylight, diffuse skylight, or sky radiation. Of the total light removed from the direct solar beam by scattering in the atmosphere (approximately 25 percent of the incident radiation), about two-thirds ultimately reaches the earth as diffuse sky radiation.
Scattering is the process by which small particles suspended in a medium of a different index of refraction redirect a portion of the incident radiation in all directions. In elastic scattering, no energy transformation results, only a change in the spatial distribution of the radiation. The science of optics usually uses the term to refer to the deflection of photons that occurs when they are absorbed and re-emitted by atoms or molecules.
posted by bea ghen at 12:59 AM
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