Why does sky appear blue?

Explanation

Blue colour of the sky is due to scattering of sunlight by air molecules. According to Rayleigh.s law, intensity of scattered light,`Iprop(1)/(lambda^(4))`.. So blue light of shorter wavelength is scattered much more than red light of larger wavelength. The blue component is proportionally more in light coming from different parts of the sky. That is why the sky appears blue.