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. However, light from toe Sun overhead would travel relatively shorter distance. At noon, toe Sun appears white as only a little of the blue and violet colours are scattered. Near the horizon, most of the blue light and shorter wavelengths are scattered away by the particles. Therefore, toe light that reaches our eyes is of longer wavelengths. This gives rise to the reddish appearance of the Sun..