Question

With the help of scattering of light, explain the reason for the difference in colours of the Sun as it appears during sunset/sunrise and noon.

Answer 1

At the time of sunrise and sunset, when the Sun is near the horizon, sunlight travels a greater distance through the atmosphere to reach us. During this time, most of the shorter wavelengths present in it are scattered away from our line of sight by the molecules of air and other fine particles in the atmosphere. So, light reaching us directly from the rising or setting Sun consists mainly of the longer wavelength red colour because of which the Sun appears red. Thus, at sunrise and sunset, the Sun and the surrounding sky appear red.

At noon, the Sun is overhead. So, the sunlight has to travel a relatively shorter distance. Hence, there is only slight scattering of shorter wavelengths of blue and violet colour. Therefore, the Sun appears mostly white.