Why Is It Quiet After It Snows?

After a snowfall, the world seems hushed -- for a while, at least. Learn why fresh snow muffles sound in this episode of BrainStuff, based on this article: https://science.howstuffworks.com/nature/climate-weather/atmospheric/quieter-after-snow.htm

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff,
Lauren Vogel Bomb Here. Have you ever noticed how after
a big snowfall, the landscape gets very quiet and everything
looks like it's covered in that insulation that you find
in the walls of houses. Things that had a distinct
shape before wheelbarrows, mailboxes, parked cars all become muffled lumps,

(00:27):
and the ambient noise were also used to is suddenly gone.
Some of this has to do with the fact that
the heavy snow can result in folks staying inside, cutting
down on traffic noise and the sounds of kids playing.
But there's something else too. Fresh snow actually is kind
of like nature's blow in insulation. Snow makes everything it

(00:49):
falls upon looks so lumpy because each snowflake is an
irregular shape, a six sided crystalline structure that doesn't lend
itself to stacking neatly atop other snowflakes. As billions of
snowflakes fall on top of one another, they don't merge
together and flow off of the landscape like rain does. Instead,
they pile up on each other like a bunch of orgamy,

(01:10):
a creating a material that has lots of tiny holes
between each flake. This porous material smooths out all the
sharp edges that usually make the things that snowfalls upon
distinguishable from each other, and those little nooks and crannies
between the snowflakes allow sound waves to enter, but then
strip them of their energy as the waves make their

(01:31):
way through that fluffy material. The sound travels in mechanical waves.
If you've ever heard the tagline from the movie Alien
in space, no one can hear you scream. That's because
space is relatively empty of stuff, and in order for
something to make noise, physical molecules of stuff, be they gaseous, liquid,

(01:52):
or solid, must be jiggled around in order for the
sound waves to be transmitted. A temperature also affects how
quickly waves can move. They speed up in warmer weather
and slow down when it gets cold. Not only can
sound waves in cold weather be a little sluggish, but
falling snow can interfere with them, making sounds and a
winter wonderland seem muffled. A blanket of fresh snow also

(02:17):
does a lot to dampen noise. The absorption of sound
is measured using a scale called sound absorption coefficient. Alpha,
which measures how well a material absorbs sound on a
scale from zero to one. The sound absorption rating for
snow is between zero point five to zero point nine,
which means, at its most effective, a few inches of

(02:38):
new fallen snow provides an impressive amount of acoustic insulation
for a lot of different frequencies of sound. A one
study published in twenty sixteen found that a couple inches
of snow can absorb roughly sixty percent of ambient sound,
but that quiet doesn't last long. The sound dampening air
pockets and snow break down not long after snowfalls. That's

(03:01):
because the shape of the delicate snowflakes changes pretty rapidly
once they settle to the ground. As they begin to
snowgle in together and or melt, the space between them shrinks,
leaving fewer spaces for sound to travel and get trapped.
In addition to that, oh once the sun hits the snow,
a thin layer of ice forms on top almost immediately,

(03:22):
turning that porous material that trapped noise in its first
hours into a sound wave reflecting surface. And that means
that it turns that silent landscape into a sort of amphitheater.
So the next time you hear that hush of a
new fallen snow, enjoy it. It probably won't last long.

(03:45):
Today's episode is based on the article why does it
get so Quiet after a Snowfall? On howstworks dot com
written by Jesselyn Shields. The Brainstuff is production by Heart
Radio in partnership with HowStuffWorks dot Com and is produced
by Tyler Klang. Four more podcasts my heart Radio, visit
the iHeartRadio app, Apple Podcasts, or wherever you listen to
your favorite shows,