Question

write the reason for appearance the red colour of sun during sunrise and sunset ? fast it is urgent

Answer 1

During sunset and sunrise the distance between Earth & Sun is   maximum .As blue light has low wavelength it scattered and cannot reach the Earth while red light has maximum wavelength,scattered the least and reaches us during sunrise and sunset.

Answer 2

Sun appears red at sunrise and sunset : At sinrise and sunset, sun is closer to the horizon. The sunlight passes through denser layer of air and covers larger distance before reaching our eyes. Most of the blue light gets scattered. The light that reaches our red. That is why the sun appears red at sunrise. 

At noon, the sun is overhead. The sunlight passes through rares layers of air and covers shorter distance before reaching our eye. So, almost all colours of light are scattered equally. Hence the sun appears white