Precipitation (meteorology)

Precipitation (meteorology)

Precipitation in meteorology refers to any product of the condensation of atmospheric water vapor that falls under gravity from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, graupel, and hail. Precipitation forms via collision with other rain drops or ice nucleation.

Types of Precipitation

Drizzle

Drizzle is a light liquid precipitation consisting of liquid water drops smaller than those of rain – generally smaller than 0.5 mm (0.02 in) in diameter. Drizzle is normally produced by low stratiform clouds and stratocumulus clouds.

Rain

Rain is a type of precipitation where water droplets fall to the ground from the cloud. It is the most common form of precipitation and important for the water cycle.

Sleet

Sleet is defined as a form of precipitation consisting of ice pellets, often mixed with rain or snow.

Snow

Snow is precipitation in the form of ice crystals. It originates in clouds when temperatures are below the freezing point.

Graupel

Graupel, also called soft hail or snow pellets, is precipitation that forms when supercooled water droplets are collected and freeze on falling snowflakes.

Hail

Hail is a form of solid precipitation. It is distinct from sleet, though the two are often confused for one another. It consists of balls or irregular lumps of ice, each of which is referred to as a hailstone.

Formation

Precipitation forms as smaller droplets coalesce via collision with other rain drops or by ice nucleation either from liquid water or from the deposition of water vapor on ice nuclei.

Measurement

Precipitation is measured using rain gauges. Rainfall amounts can be estimated by weather radar.

Effects

Precipitation has multiple effects on the environment and the living organisms within it. It is a key component in the water cycle, including the distribution and deposition of particulate matter within the atmosphere.

See also

• Cloud
• Fog
• Mist
• Dew