The silence of snowfall

How sound is dampened in a blizzard


There’s something special about the quality of sound when it snows. Those who live in parts of the world that experience snowfall know it well — an eerie, muted stillness that you hear from your bed, which betrays the season’s first snowflakes before you fling open the curtains in excitement.

Scattering

But the question of why this happens is pretty interesting. An obvious first thought is that the snowflakes are getting in the way of the soundwaves, scattering them and meaning that less of the sound reaches you.

That does happen, but it’s not a huge effect because snowflakes are pretty small compared to the wavelength of the sound we care about. Low, bass-y frequencies (booms) are almost unaffected by snowfall, whereas high, treble-y frequencies (hisses) are scattered a little more but still not enough to credit the beautiful snowy stillness to.

Absorption

To adequately explain this phenomenon, you need to look at two more things that happen when it snows. The first is how sound is absorbed by surfaces. Acoustic science has shown that surfaces that are insulating but have small holes in are very effective at absorbing sound, which is why recording studios tend to cover their walls with foam.

As the Inuit populations of the Arctic know very well, snow is a great insulator too, and its exterior surface has many small holes that air can get inside. When sound bounces off snow, then, it gets absorbed before reaching you, reducing both the volume and reverberation.

Curving Sound

That’s only part of the story, though. The other has to do with the temperature of air masses above you. Sound tends to curve towards colder air because cold air is denser than warm air and sound travels more slowly through denser materials.

When snow is falling, you usually have warmer air near the surface and cold air above. This makes sound curve up and away into the atmosphere and eventually out to space without ever being heard of again.

Putting it together

So putting all those effects together, you end up with soundwaves being absorbed by snowy surfaces, being curved up and out into space, and scattered (a tiny bit) along the way by falling snowflakes.

As a result, you can hear nearby sounds clearly but those further away are muted before they get to you, creating a wonderful, peaceful, stillness that’s unique to snowy weather.


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