Snowfall
In short
Snowfall is the descent of ice crystal flakes from the atmosphere to the ground. It occurs when water vapour freezes into crystals within clouds and falls as solid precipitation.
In plain words
When the air is cold enough, water turns into tiny ice crystals instead of raindrops. These crystals stick together to form flakes that fall from the sky and pile up on the earth.
A simple example
A heavy blizzard can cover a garden in several inches of white powder in just a few hours. This layer of snow stays on the grass until the temperature rises.
Why it matters
Snowfall provides essential water for rivers and soil when it melts. However, too much snow can cause transport delays and dangerous conditions for buildings.
Easy to mix up
Do not confuse snowfall with sleet, which consists of small ice pellets rather than soft, crystalline flakes.