Grades K–2 · Earth & Space
Why does a boot leave a dent in fresh snow?
Fresh snow can look like a solid white blanket, but it has many tiny ice grains with air spaces between them. The grains are not packed as tightly as they could be.
In the diagramA boot packs loose ice grains closerloose snow + airtighter packing
A boot pushes down with the person’s weight. Grains can break, move and pack closer together. Some of the air is pushed away as the snow under the boot takes up less space.
The packed area can stay lower after the boot lifts, leaving a footprint. The snow has been squeezed into a denser arrangement. It does not all have to turn into liquid water to leave the dent.
About this explanation
Starting knowledge: Recognize snow on the ground and the downward push from a person standing.
Sources
- National Snow and Ice Data Center — Science of Snow