Question

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

Answer 1

Light from the Sun near the horizon passes through thicker layers of air and larger distance in the earth’s atmosphere before reaching our eyes. Near the horizon, most of the blue light and shorter wavelengths are scattered away by the particles. Therefore, the light that reaches our eyes is of longer wavelengths (reddish). This gives rise to the reddish appearance of the Sun.

At noon, the Sun is nearly overhead, and hence the light would travel relatively shorter distance. At noon, the Sun appears white as only a little of the blue and violet colours are scattered.