Cumulus humilis cloud

Cumulus humilis clouds
Cumulus humilis
Abbreviation	Cu
Symbol
Genus	Cumulus (heap)
Species	humilis (humble)
Altitude	500 - 3000 m (1,500 - 10,000 ft)
Precipitation cloud?	Usually No
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Cumulus humilis is a low to middle cloud with small vertical extent (Family D1) that is commonly referred to as "fair weather cumulus". In hot countries and over mountainous terrain these clouds occur at up to 6000 meters altitude, though elsewhere they are typically found lower.

They are formed by rising warm air that has been heated by the ground, which in turn has been heated by the sun. They have a limited depth (technically known as showing no significant vertical development). This indicates that the temperature in the atmosphere above them either drops off very slowly or not at all with altitude (see Lapse rate). While cumulus humilis may be accompanied by other cloud types, when they appear in a clear sky (see picture), they are an indicator of pleasant weather for the next several hours. Though at times, these clouds collapse into stratocumulus clouds, and cover much of the sky.

Air below the cloud base can be quite turbulent, giving occupants of light aircraft an uncomfortable ride.^{[citation needed]} To avoid turbulence where such clouds are present, pilots may climb above the cloud tops. However, glider pilots actively seek out the rising air to gain altitude.

Forecast

If these clouds are present in the morning it is a sign of an unstable atmosphere. Larger clouds and possibly thunderstorms could form throughout the day to cause bad or severe weather in the afternoon or evening. Cumulus humilis clouds are not rain clouds but could show an impending storm in the future.

External links

• Cumulus humilis