The blue color of the sky is caused by the scattering of sunlight off the molecules of the atmosphere. This scattering, called Rayleigh scattering, is more effective at short wavelengths (the blue end of the visible spectrum). Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the spectrum.

Yes.. more correctly worded and in more detail.. although.. this is still talking about the frequency of the light rays.. :) I just didn't have the time to go into depth..

Blue Sky