Question

How can we explain the reddish appearance of sun at sunrise or sunset? Why does it not appear red at noon?

Answer 1

Colours near the red end of the spectrum scatter the least. This
happens because of short wavelength of reddish colours. During sunset and sunrise,
sunlight needs to travel more distance to reach us, Red colour is able to reach
us because it is scattered the least.Hence, sky appears reddish during sunrise/sunset.

The sky appears reddish during sunrise/sunset but it appears white
at noon. During noon, the sunlight has to travel less distance to reach us. Most
of the colours reaching us get scattered. Due to this, sky appears white at noon.