Definition: Snow: Precipitation of ice crystals, singly or stuck together, that falls from a cloud.
The form, size and concentration of snow crystals differ considerably according to the temperature and supersaturation at which they develop. A fall of snow usually includes various types of snow crystals and almost all types of crystal may be observed during a single fall of snow.
Small droplets of frozen water are often attached to snow crystals. If present in great numbers, these can obscure the crystalline structure of the snow.
At temperatures warmer than about –5 °C, the crystals generally stick together to form snowflakes.