Quote:
Originally posted by saturno7
I think I know this one, but I'm not sure if I can explain it in English... :D
The sun light must travel from the Sun to the Earth, suffering from scattering during its trip. The air molecules in the terrestrial atmosphere scatters the blue and violet components of the white sun light and let the rest pass without dispersion, because of the size of these molecules (smaller than the red and orange components wave lenght, but similar to the wave length of the blue component). The violet component suffers from scattering more than the blue one, but the human eye is more sensitive to blue, so we see the sky blue and not violet.
That's the Rayleigh effect, I think.
I hope I have explain myself more or less well in my strange English.. ;)
Really the Rayleigh scattering depends on the fouth power of the frequency, this is why the blue and violet component of the light is more scattered than the red. This effect causes sky's blue appearance, because when we look at the sky we see the scattered light which has more blue components than red. And this is also why the sky's appearance at sunset is red, because we see the light not scattered, wich has more red components.