When I was a child I asked myself the same questions that most children asked themselves, and their parents....
Why is the Sky Blue?
Blue light has a shorter wavelength than red light; therefore, the blue light is scattered more.When blue light waves hit the N2 and O2 particles it sends the blue light in all directions. After being scattered the sky appears blue to us. However, blue isn't the only color of light that is scattered by our atmosphere. All colors that have a longer wavelength then blue are scattered aswell. There is also yellow, green, and red! The reason we see blue the most is because it has an extremely short wavelength causing it to be scattered far more than others.
Ok, I lied! Blue isn't scattered the most... Violet is! The only problem with violet is our eyes aren't sensitive enough to see it!
Could you imagine a purple sky!!
Important Definitions:
Scattering -Of a wave propagating in a material medium, a phenomenon in which the direction, frequency, or polarization of the wave is changed when the wave encounters discontinuities in the medium, or interacts with the material at the atomic or molecular level.
Refraction - the bending of light that takes place at a boundary between two materials having different indices of refraction. Refraction is due to a change in the speed of light as it passes from one medium to another.
During the middle of the day the sky is blue because the light goes through the atmosphere and since blue has short wavelength is scattered. Well, at sunset the light has to go through significantly more atmosphere. That explains why the sunset is red! All the blue light gets scattered out by time the light reaches our eyes. The only light that is left are the colors with long wavelengths.
Wow.