Precipitation

rainfallhydrometeorannual precipitationprecipitationswetorographic precipitationhydrometeorsprecipitateprecipitatedrain
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity.wikipedia
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Drizzle

drizzlydrizzlingmizzle
The main forms of precipitation include drizzle, rain, sleet, snow, graupel and hail.
Drizzle is a light liquid precipitation consisting of liquid water drops smaller than those of rain – generally smaller than 0.5 mm in diameter.

Hail

hailstormhailstoneshailstone
The main forms of precipitation include drizzle, rain, sleet, snow, graupel and hail. Frozen forms of precipitation include snow, ice needles, ice pellets, hail, and graupel.
Hail is a form of solid precipitation.

Graupel

Snow pelletssmall hailsoft hail
The main forms of precipitation include drizzle, rain, sleet, snow, graupel and hail. Frozen forms of precipitation include snow, ice needles, ice pellets, hail, and graupel.
Graupel (Enɡlish: ), also called soft hail or snow pellets, is precipitation that forms when supercooled water droplets are collected and freeze on falling snowflakes, forming 2 - 5 mm balls of rime.

Thundersnow

snowthunder
Thundersnow is possible within a cyclone's comma head and within lake effect precipitation bands.
Thundersnow, also known as a winter thunderstorm or a thundersnowstorm, is an unusual kind of thunderstorm with snow falling as the primary precipitation instead of rain.

Fog

advection fogfreezing fogground fog
Thus, fog and mist are not precipitation but suspensions, because the water vapor does not condense sufficiently to precipitate.
Fog commonly produces precipitation in the form of drizzle or very light snow.

Water vapor

water vapourvaporevaporation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity.
In some countries, the evaporation rate far exceeds the precipitation rate.

Water cycle

hydrological cyclehydrologic cyclewater
Precipitation is a major component of the water cycle, and is responsible for depositing the fresh water on the planet.
The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow.

Climate

climaticclimate systemclimates
Given the Earth's surface area, that means the globally averaged annual precipitation is 990 mm, but over land it is only 715 mm. Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes.
It is measured by assessing the patterns of variation in temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables in a given region over long periods of time.

Orographic lift

orographicorographic liftingrelief precipitation
Mechanisms of producing precipitation include convective, stratiform, and orographic rainfall.
As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and create clouds and, under the right conditions, precipitation.

Wet season

rainy seasonmonsoon seasonwet
The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.
When the wet season occurs during a warm season, or summer, precipitation falls mainly during the late afternoon and early evening.

Ice pellets

sleetice pelletrefreezed snow
Frozen forms of precipitation include snow, ice needles, ice pellets, hail, and graupel.
Ice pellets are a form of precipitation consisting of small, translucent balls of ice.

Fresh water

freshwaterfreshlimnic
Precipitation is a major component of the water cycle, and is responsible for depositing the fresh water on the planet.
The source of almost all fresh water is precipitation from the atmosphere, in the form of mist, rain and snow.

Cyclone

cyclonescycloniccyclonic storm
Where relatively warm water bodies are present, for example due to water evaporation from lakes, lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones.
Such fronts form west of the circulation center and generally move from west to east; warm fronts form east of the cyclone center and are usually preceded by stratiform precipitation and fog.

Diamond dust

ice needles
Frozen forms of precipitation include snow, ice needles, ice pellets, hail, and graupel.
This meteorological phenomenon is also referred to simply as ice crystals and is reported in the METAR code as IC. Diamond dust generally forms under otherwise clear or nearly clear skies, so it is sometimes referred to as clear-sky precipitation.

Water

H 2 Oliquid wateraqueous
Like other precipitation, hail forms in storm clouds when supercooled water droplets freeze on contact with condensation nuclei, such as dust or dirt.
It forms precipitation in the form of rain and aerosols in the form of fog.

Stationary front

stationarystationary frontsboundary
A stationary front is often present near the area of freezing rain and serves as the foci for forcing and rising air.
A wide variety of weather can be found along a stationary front, but usually clouds, prolonged precipitation, and storm trains are found there.

Stratus cloud

stratusstratiformstratus clouds
Mechanisms of producing precipitation include convective, stratiform, and orographic rainfall. Provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus.
They mostly appear under the precipitation of major rain-bearing clouds.

METAR

aviation flight categoryaviationhourly weather forecasts
The METAR code for ice pellets is PL.
A typical METAR contains data for the temperature, dew point, wind direction and speed, precipitation, cloud cover and heights, visibility, and barometric pressure.

Rain shadow

rainshadowrainshadow effectlow snowfall
Moisture is removed by orographic lift, leaving drier air (see katabatic wind) on the descending and generally warming, leeward side where a rain shadow is observed.
At the adiabatic dew point, moisture condenses onto the mountain and it precipitates on the top and windward sides of the mountain.

Tropical cyclone

hurricanetropical stormhurricanes
Similar ascent is seen around tropical cyclones outside of the eyewall, and in comma-head precipitation patterns around mid-latitude cyclones.
Tropical cyclones also draw in air from a large area—which can be a vast area for the most severe cyclones—and concentrate the precipitation of the water content in that air (made up from atmospheric moisture and moisture evaporated from water) into a much smaller area.

Squall line

quasi-linear convective systemrain bandbanding
In mid-latitudes, convective precipitation is intermittent and often associated with baroclinic boundaries such as cold fronts, squall lines, and warm fronts.
It contains heavy precipitation, hail, frequent lightning, strong straight-line winds, and possibly tornadoes and waterspouts.

Synoptic scale meteorology

synoptic scalesynopticsynoptic-scale
Stratiform or dynamic precipitation occurs as a consequence of slow ascent of air in synoptic systems (on the order of cm/s), such as over surface cold fronts, and over and ahead of warm fronts.
Most precipitation areas occur near frontal zones.

Cumulonimbus cloud

cumulonimbusthundercloudcumulonimbus clouds
Provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus. Convective rain, or showery precipitation, occurs from convective clouds, e.g., cumulonimbus or cumulus congestus.
Most storm cells die after about 20 minutes, when the precipitation causes more downdraft than updraft, causing the energy to dissipate.

Cirrostratus cloud

cirrostratuscirrostratus cloudsCs
An elevated portion of a frontal zone forces broad areas of lift, which form clouds decks such as altostratus or cirrostratus.
Cirrostratus clouds sometimes signal the approach of a warm front if they form after cirrus and spread from one area across the sky, and thus may be signs that precipitation might follow in the next 12 to 24 hours or as soon as 6–8 hours if the front is fast moving.

Precipitation types

orographic precipitationorographic rainfallConvective rain
Convective rain, or showery precipitation, occurs from convective clouds, e.g., cumulonimbus or cumulus congestus.
In meteorology, the various types of precipitation often include the character or phase of the precipitation which is falling to ground level.