How do you appreciate the role of molecules in the atmosphere for the blue colour of the sky?

The sky appears blue due to scattering phenomenon of light.Scattering phenomenon occurs only when the size of the atom is comparable to the wavelength of light. Our atmosphere is comprised of oxygen and nitrogen molecules. So the wavelength of blue & violet is comparable to these molecules. These molecules absorb light energy from the sunlight of certain frequency and molecules gets into excited state. When they come back to ground state, they emit light matching the wavelength of blue & violet. Therefore the molecules present in air scatter the blue & violet light. As human eye is sensitive to blue more than violet, therefore the sky appears blue Also the intensity of light depends on the angle of scattering. Intensity is maximum when angle of scattering is equal to 90 degrees. This is the reason why the sky appears more blue overhead than other parts.