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Cumulus humilis, with cumulus congestus on the horizon
Abbreviation	Cu
Genus	Cumul (heap)
Altitude	Below 2,000 m (Below 6,500 ft)
Classification	Family C (Low-level)
Precipitation Cloud?	Depends. Cumulus humilis and mediocris, most likely no, but cumulus congestus, sometimes, even often yes.

Cumulus clouds are usually puffy and often have very distinct edges and usually a noticeable vertical development. They often have a popcorn-like appearance. Cells can be rather isolated or they can be grouped together in clusters. Image File history File links Wiki_letter_w. ... Image File history File linksMetadata Download high resolution version (1225x919, 1016 KB) Super Color Cumulus Medows I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... // High-level clouds Cirrus Clouds (from above) Abbreviation: Ci Cirrus clouds form above 16,500 feet (5,000 m), in the cold region of the troposphere. ... The metre, or meter (U.S.), is a measure of length. ... A foot (plural: feet or foot;[1] symbol or abbreviation: ft or, sometimes, ′ – a prime) is a unit of length, in a number of different systems, including English units, Imperial units, and United States customary units. ... Cumulonimbus capillatus incus floating over Swifts Creek, Victoria in Australia A cloud is a visible mass of condensed droplets or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. ... // High-level clouds Cirrus Clouds (from above) Abbreviation: Ci Cirrus clouds form above 16,500 feet (5,000 m), in the cold region of the troposphere. ... This article is about clouds in meteorology. ...

That makes a fundamental difference of the wind characteristics of a cumulus cloud. The main reason for this is that the first rain to fall out of the base of the cloud evaporates into the air beneath and cools it, often by several degrees. This cooled air descends the more it is cooled the more rapidly it descends. Thus instead of air rising into a cloud, not only rain falls out the cloud, but air as well. The drier the air beneath the cloud the more it is capable of being cooled by evaporation, and so long as there is enough rain coming out of the cloud the colder the air becomes. The cold air will drop out from beneath the cloud with the rain and spread out in all direction at the surface. The light wind that was moving in towards the cloud suddenly becomes a squall rushing out and away from it. Rain falls, often in grey streaks below the cloud sometimes in a dramatic arch of black cloud spreading out from the parent cloud. Rain is a source of precipitation which forms when separate drops of water fall to the Earths surface from clouds. ...

Over the sea cumulus clouds are normally found in regularly spaced lines. The best examples of these are found in the trade winds where they extend for many tens of miles. These show up a pattern in the vertical movement of air which is like a horizontal roll. Between the lines of cloud are stronger, more gusty and slightly veered winds, and beneath the lines of cloud somewhat lighter and more backed wind. The trade winds are a pattern of wind found in bands around Earths equatorial region. ...

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