Why does the sky appear blue on a clear day ?

Explanation

Blue colour of the sky can be explained by Rayleigh scattering. The amount of scattering is inversely proportional to the fourth power of the wavelength. When light from the sun travels through earth.s atmosphere, it gets scattered, by large number of gaseous molecules. The blue light of shorter wavelength is scattered more than the red light of larger wavelength. Due to this, blue colour predominates and the sky appears blue.