It is the name given to water drops from a cloud, which fall towards the ground. Whilst falling through different layers of atmosphere, the water drops may freeze into soft ice (snow) or into hard ice (hail). Sometimes, precipitation evaporates completely, during its transit through the atmosphere, and does not reach the ground, it may then be visible as vertical streamers below clouds and is called “Virga”. Mist and Fog are not called precipitation because the water droplets remain suspended in the air and do not fall.
The principal forms are:
Drizzle– Water droplets with diameters between 200 pm and 500 pm.
Rain- Water droplets with diameters exceeding 500 pm.
Snow or Snowflakes– Small ice crystals or aggregates of ice crystals.
Hail– Balls of ice of varying size.
Sleet– Mixture of rain and snow.