|Altitude||Below 2,000 m
(Below 6,000 ft)
|Classification||Family C (Low-level)|
|Precipitation cloud?||Drizzle, freezing drizzle or snow grains|
A stratus cloud (St) is a cloud belonging to a class characterized by horizontal layering with a uniform base, as opposed to convective clouds that are formed by rising thermals (these are also known as cumuliform clouds). More specifically, the term stratus is used to describe flat, hazy, featureless clouds of low altitude varying in color from dark gray to nearly white. Stratus clouds may produce a light drizzle or snow. A "cloudy day" commonly features a sky filled with stratus clouds obscuring the disk of the sun. These clouds are essentially above-ground fog formed either through the lifting of morning fog or through cold air moving at low altitudes over a region. Some call these clouds "high fog" for the fog-like cloud. While light rain may fall, this cloud does not indicate much meteorological activity.
A stratus cloud can form from stratocumulus spreading out under an inversion, indicating a continuation of prolonged cloudy weather with drizzle for several hours and then an improvement as it breaks into stratocumulus. Stratus clouds can persist for days in anticyclone conditions. It is common for a stratus to form on a weak warm front, rather than the usual nimbostratus.
- Ackerman, Steven A. and John A. Knox, Meteorology: Understanding the Atmosphere. Brooks Cole, 2003.
- USA Today Weather site on stratus clouds
- Common cloud types
- Weather Wiz Kids
- (Out of link) http://www.ace.mmu.ac.uk/eae/weather/older/stratus_clouds.html
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