Can Snow Keep Things Warm? A Snow Den Experiment

Snow is cold, so how can it keep anything warm? This experiment shows that snow is a good insulator, and it explains why mice, voles and other small animals survive under the snow all winter.

The experiment

You need: snow (or crushed ice), two identical jars of warm water, a thermometer, a ruler and a timer.

Fill both jars with the same amount of warm water and record the temperature.
Leave one jar sitting on top of the snow. Bury the other under 15 to 20 cm (6 to 8 in) of snow, packed gently.
After 30 minutes, take both temperatures.

What usually happens

The buried jar cools more slowly than the exposed one. Wind and open air take heat from the jar on top. The snow around the buried jar traps still air between the crystals, which slows heat leaving.

Probe the snow

Push a thermometer into the snow at different depths: on the surface, 5 cm down and at the ground. In many places, the air above is far colder than the ground under a deep snow layer. The snow acts as a blanket. Your results will depend on the snow depth and conditions, so record them.

Why animals benefit

Small animals such as voles and mice tunnel in the subnivean space, a gap between the snow and the ground, where temperatures stay much steadier than in the air above. A deep snow cover can mean the difference between surviving and freezing. People have also built snow shelters for the same reason.

If you don’t live where it snows

Use crushed ice or a cooler of ice, and test insulation with other materials: leaves, foam, sand. Or save this for a trip.

Common mix-ups

“Snow is warm.” It’s cold, but it slows the movement of heat.
“Insulation makes things warm.” It slows heat flow from a warm thing.

The full lesson is Can snow keep things warm? in Winter Science: Ice, Snow and Staying Warm. Sign up for three lessons free.