Question

at noon sun appears white but near the horizon it appears red why​

Answer 1

Light is a spectrum made of 7 different colors-ROYGBIV(red,orange,yellow, green,zarurat blue, indigo and violet).Red colour has the highest wavelength and blue and it's shades have the least.

At noon, the sun is at the top and the light rays coming from it have to travel less distance in the atmosphere of earth. Hence, all colours get scattered very less, even blue.

In evening, the sun is not at the top and the light rays from sun have to travel more distance in the earth's atmosphere. The difference is nearly of 150kms. In this long run, blue colour and all its shades get scattered the most whereas red, orange, yellow get scattered the least.

That's why we see the sun reddish in the evening.

The phenomenon behind it is scattering of light.

Answer 2

At noon sun is overhead and the sun rays have to travel a much shorter distance. Thus the scattering of light is much less and sun appears white.

At the horizon, optical density of the atmosphere is much higher. Therefore light colors with lower wavelengths get scattered back into the space, which is why only red light, which has the highest wavelength reaches our eyes and we see that the sun is red.