Question

Why does everything feel so quiet after a snowfall?

Answer 1

Hint Sound travels in the form of longitudinal waves through different mediums in the form of compressions and rarefactions. Porous surfaces are very good at absorbing sounds and not letting them propagate further. Using this property we can deduce the reason.

Complete step by step answer
Sound travels in the air in the form of regions of high and low pressure which are called compressions and rarefactions. While travelling they are absorbed, reflected, and scattered by different kinds of surfaces.
When fresh snow falls, the structure of snow crystals is porous in nature. This gives it the ability to absorb sound very efficiently. As a result, the noise we generally experience in a city environment is absorbed by the snow that is present in all directions. So sound does not travel very further in such a case. So different ambient noises that we usually hear like car engine noises, horns, and mechanical noises from different machines, etc. are all effectively absorbed by the sound crystals, and sound cannot travel a large distance hence making everything feel very quiet.
The effectiveness of the absorbance of sound depends on the amount of snowfall that has fallen too but more snowfall absorbing more sound and making everything seem quieter. But even an inch of snowfall will start absorbing enough sound to make a noticeable decrease in the amount of ambient sounds that we hear.

Note
Snow is only able to absorb sound when it is fresh and has a good porous crystal structure. Once it melts and refreezes, it becomes hard and its composition changes and it can no longer absorb sound very well but will rather reflect it very efficiently. Things do not seem very quiet after that has happened.