After a heavy rainstorm, why does the sky turn deeper blue in color?

Question

After a heavy rainstorm, why does the sky turn deeper blue in color?

Answer 1

The reason the sky is blue, is described by a phenomenon called Rayleigh Scattering. In our atmosphere there are molecules of size near the wavelength of light, due to their small size they tend to disperse white light into it's colours. It so happens that blue light is dispersed the most.

        Apart from these molecules, there are innumerable number of dust particles in the atmosphere, so after the first dispersion, blue light continues to be reflected off each dust particle, until it reaches our eye. With every reflection blue light looses intensity which is why the sky appears light blue.

        Now it rains,

the raindrops, as they fall,  imbibe the dust particles present in the atmosphere. Thus the number of dust particles are significantly reduced. Hence the number of subsequent reflections are greatly reduced. Thus Deep Blue.

Answer 2

Thats because an increase in the amount of water vapour in the air which acts to diffract the shorther wavelength of the visible spectra.