Precipitation is a form of water from the atmosphere. It is a term in meteorology, and includes rainsnowsleetdewfrost, and hail. These form from atmospheric water vapor and fall under gravity.

Fog and mist are not precipitation but suspensions. In that case, the water vapor does not condense sufficiently to precipitate.

Raindrops form when the water droplets making up the clouds begin to collide. Millions have to collide together to form one raindrop. Sometimes the drops rise high enough and get cold enough to turn into ice. Those collide and grow and fall as ice or snow.

If liquid, precipitation can be measured using a rain gauge. The most common form of solid precipitation is snow. Snow is made when temperatures are so cold that water vapor changes directly to solid crystals. Frozen rain is hail or sleet.

Rain is when water falls from clouds in droplets that are bigger than 0.5 mm. Droplets of water that are about 0.2 mm to 0.45 mm big are called drizzle. Rain is a kind of precipitation. Rain is part of the water cycle.


Condensation and coalescence are important parts of the water cycle.


rainstorm is a sudden heavy fall of rain. It may cause flash floods in valleys. Heavy rain for a long time may make floods on floodplains. Rivers overflowing can destroy houses and drown people. Also, landslides may happen.

Snow is a form of ice. Snow forms when water in the atmosphere becomes frozen. Snow comes in all different shapes and sizes.

Snowflake viewed in an optical microscope

Sleet is a term for ice pellets that is used in the United States and Canada. Ice pellets are a type of frozen precipitation. They are balls of ice. Ice pellets are usually smaller than hailstones. Sometimes, ice pellets bounce when they hit the ground.

Sleet on the ground

A piece of hail (called a hailstone) is a lump of ice that falls out of a storm cloud. About 5,000 hailstorms a year in the United States of America make hail 3/4 of an inch or bigger.

Hailstones (ice) on ground after a storm


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