Have you ever noticed that the sound snow makes when you walk on it changes as the temperature drops?
It goes from a "crunch" sound to a "squeaking" sound as it gets colder outside.
There are a few theories about why the sound of snow changes depending on the temperature, but according to the University of Wisconsin it could be because when it's warmer than -10C, the pressure of your boot may be causing a thin layer of snow to melt, creating a crunch.
When it's colder than -10C, you're hearing ice crystals in the snow being crushed -- and that creating a squeaking sound as well.
"A layer of snow is made up of ice grains with air in between the ice grains," the International Ski Federation says on its website.
"Because the snow layer is mostly empty air space, when you step on a layer of snow you compress that layer a little or a lot, depending on how old the snow is."
When the snow compresses the ice grains make contact, creating friction or resistance.
Colder temperatures generate greater friction between the ice grains -- and the colder the temperature the deeper the crunch, which you can see in the video above.