Science
How does snow form?
Snow forms when water vapor high in cold clouds freezes directly into ice crystals, which grow into six-sided snowflakes and fall. Each flake builds its intricate, unique shape as it drifts through air of changing temperature and moisture.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how snow works.
Step by step
- 1Water vapor in cold clouds freezes straight onto tiny particles.
- 2Ice crystals grow into six-sided (hexagonal) shapes.
- 3Their pattern depends on the temperature and humidity they pass through.
- 4Crystals clump into snowflakes and fall when heavy enough.
- 5The air must be cold all the way down for it to stay snow.
Frequently asked questions
- Why are snowflakes six-sided?
- Water molecules bond in a hexagonal pattern as they freeze, so growing ice crystals naturally take on six-fold symmetry.
- Why is every snowflake different?
- Each takes a unique path through varying temperature and moisture, and those tiny differences shape its exact pattern.
- Why does it sometimes rain instead of snow?
- If the air near the ground is above freezing, falling snow melts into rain before it lands.