Changes

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*Date: [http://www.wikipedia.org/wiki/16th_Century 1502]

*Date: [http://www.wikipedia.org/wiki/16th_Century 1502]

In meteorology, '''precipitation''' (also known as one of the classes of hydrometeors, which are [[atmospheric]] [[water]] [[phenomena]]) is any product of the [[condensation]] of atmospheric  [[water]] vapor that is pulled down by [[gravity]] and deposited on the [[Earth]]'s [[surface]]. The main [[forms]] of precipitation include rain, snow, ice pellets, and [http://en.wikipedia.org/wiki/Graupel graupel]. It occurs when the [[atmosphere]], a large [[gaseous]] solution, becomes [[saturated]] with [[water]] vapour and the water [[condenses]], falling out of solution (i.e., precipitates). Two [[processes]], possibly [[acting]] [[together]], can lead to [[air]] becoming [[saturated]]: cooling the air or adding [[water]] vapour to the air. [http://en.wikipedia.org/wiki/Virga Virga] is precipitation that begins falling to the [[earth]] but evaporates before reaching the [[surface]]; it is one of the ways air can become [[saturated]]. Precipitation forms via collision with other rain drops or ice [[crystals]] within a [http://en.wikipedia.org/wiki/Cloud cloud].

In meteorology, '''precipitation''' (also known as one of the classes of hydrometeors, which are [[atmospheric]] [[water]] [[phenomena]]) is any product of the [[condensation]] of atmospheric  [[water]] vapor that is pulled down by [[gravity]] and deposited on the [[Earth]]'s [[surface]]. The main [[forms]] of precipitation include rain, snow, ice pellets, and [http://en.wikipedia.org/wiki/Graupel graupel]. It occurs when the [[atmosphere]], a large [[gaseous]] solution, becomes [[saturated]] with [[water]] vapour and the water [[condenses]], falling out of solution (i.e., precipitates). Two [[processes]], possibly [[acting]] [[together]], can lead to [[air]] becoming [[saturated]]: cooling the air or adding [[water]] vapour to the air. [http://en.wikipedia.org/wiki/Virga Virga] is precipitation that begins falling to the [[earth]] but evaporates before reaching the [[surface]]; it is one of the ways air can become [[saturated]]. Precipitation forms via collision with other rain drops or ice [[crystals]] within a [http://en.wikipedia.org/wiki/Cloud cloud].

Moisture overriding [[associated]] with [[weather]] fronts is an overall major [[method]] of precipitation production. If enough moisture and upward [[motion]] is present, precipitation falls from convective clouds such as [http://en.wikipedia.org/wiki/Cumulonimbus cumulonimbus] and can [[organize]] into narrow [http://en.wikipedia.org/wiki/Rainbands rainbands]. 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 http://en.wikipedia.org/wiki/Cyclone cyclonic] [[flow]] around the backside of [http://en.wikipedia.org/wiki/Extratropical_cyclone extratropical cyclones]. Lake-effect snowfall can be locally heavy. Thundersnow is possible within a [http://en.wikipedia.org/wiki/Extratropical_cyclone cyclone]'s [http://en.wikipedia.org/wiki/Extratropical_cyclone#Surface_pressure.2FWind_distribution comma head] and within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. The movement of the [http://en.wikipedia.org/wiki/Monsoon_trough monsoon trough], or [http://en.wikipedia.org/wiki/Intertropical_convergence_zone intertropical convergence zone], brings rainy seasons to [http://en.wikipedia.org/wiki/Savannah savannah] climes.

Moisture overriding [[associated]] with [[weather]] fronts is an overall major [[method]] of precipitation production. If enough moisture and upward [[motion]] is present, precipitation falls from convective clouds such as [http://en.wikipedia.org/wiki/Cumulonimbus cumulonimbus] and can [[organize]] into narrow [http://en.wikipedia.org/wiki/Rainbands rainbands]. 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 [http://en.wikipedia.org/wiki/Cyclone cyclonic] [[flow]] around the backside of [http://en.wikipedia.org/wiki/Extratropical_cyclone extratropical cyclones]. Lake-effect snowfall can be locally heavy. Thundersnow is possible within a [http://en.wikipedia.org/wiki/Extratropical_cyclone cyclone]'s [http://en.wikipedia.org/wiki/Extratropical_cyclone#Surface_pressure.2FWind_distribution comma head] and within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. The movement of the [http://en.wikipedia.org/wiki/Monsoon_trough monsoon trough], or [http://en.wikipedia.org/wiki/Intertropical_convergence_zone intertropical convergence zone], brings rainy seasons to [http://en.wikipedia.org/wiki/Savannah savannah] climes.

==Types==

==Types==

Precipitation is a major component of the [[water]] [[cycle]], and is [[responsible]] for depositing most of the fresh [[water]] on the [[planet]]. Approximately 505,000 km3 (121,000 cu mi) of water falls as precipitation each year, 398,000 km3  (95,000 cu mi) of it over the [[oceans]]. Given the [[Earth]]'s [[surface]] area, that means the globally-[[averaged]] annual precipitation is 990 millimetres (39 in).

Precipitation is a major component of the [[water]] [[cycle]], and is [[responsible]] for depositing most of the fresh [[water]] on the [[planet]]. Approximately 505,000 km3 (121,000 cu mi) of water falls as precipitation each year, 398,000 km3  (95,000 cu mi) of it over the [[oceans]]. Given the [[Earth]]'s [[surface]] area, that means the globally-[[averaged]] annual precipitation is 990 millimetres (39 in).