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Scattering of light is the phenomenon in which a part of the incident light is dispersed in different directions.

light of longer wavelengths at the red end. Thus, when sunlight passes through the atmosphere, the fine particles in the air scatter blue colour (shorter wavelengths) more strongly than red. The scattered blue light enters our eyes, and hence, the clear sky appears blue.

Sun appears reddish at sunrise: 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, 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 as well as the surrounding sky appears red.