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Mammatus Clouds
Mammatus clouds, pouch-like formations that are generally found protruding from the underside of cumulonimbus clouds. However, they can also develop underneath cirrocumulus, altostratus, altocumulus and stratocumulus. In the U.S., mammatus occurring in cumulonimbus clouds are more common and are often indicative of a particularly strong--or even tornadic--storm.
Mammatus clouds are a rare example of clouds in sinking air (most clouds form in rising air). For mammatus to form, the sinking air must be cooler than the air around it and have high liquid water or ice content. They derive their name from their appearance--the baglike sacs that hang beneath the cloud resemble cow's udders.
Research on clouds and weather phenomena is performed at the National Center for Atmospheric Research (NCAR), supported by the National Science Foundation (NSF) and other federal agencies to provide facilities and support for a wide range of studies in the atmospheric and related sciences. NCAR is managed by the University Corporation for Atmospheric Research (UCAR), a nonprofit consortium of universities that grants Ph.D.s in fields related to atmospheric science. UCAR's primary function is managing NCAR. To learn more, visit the NCAR website, Here.
Credit: ©University Corporation for Atmospheric Research
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