If you ever went outside on a winter day, during or after a snow storm you may have noticed the relative silence of your surroundings. Not only does everything look as if it is covered with a big white blanket, it also sounds as such. The surroundings are beautifully quiet.

The typical acoustics encountered after a snow storm are generally not caused through dampening of the sound by falling snowflakes, since this phenomenon is also observed some time after a snow fall. In fact, during the winter there is also often a temperature inversion: a layer of cold air directly below a layer of warmer air, that will actually increase the propagation of sound through the cold air.

Then, what causes the typical snow acoustics? First of all, there may actually be fewer sources of noise outside, since more people tend to stay home after heavy snow fall. Secondly, the generation of sound from each source may be significantly changed by a layer of snow on the soil, causing a dampening of the sound generation. Finally, a layer of fallen snow can absorb sound quite efficiently; a snow coverage of approximately 2.5 cm will only transmit 25% of the sound1. Thus, a significant part of the sound that would otherwise be reflected by the street or soil will be absorbed by the snow blanket.

As described in:
Prof. Dr. Marcel G. J. Minnaert, de Natuurkunde van het Vrije Veld, 1939.
1: Nature, 143, 80, 1939

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