Precipitation

In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds under gravity, carrying most of the fresh water that reaches land and ocean surfaces on the planet. Its main forms are drizzle and rain, sleet or mixed rain and snow, and frozen forms such as snow, ice pellets, graupel and hail, along with freezing rain and freezing drizzle that freeze on contact with the ground. It forms as small droplets or ice crystals inside a cloud collide and coalesce into larger, heavier particles that air currents can no longer support, at which point they fall; fog and mist are not precipitation because their water vapor never condenses enough to fall. Globally, about 505,000 cubic kilometres of water falls as precipitation each year, averaging 990 millimetres worldwide but only 715 millimetres over land.