Mammatus Clouds

Provided by: David Bowler, USRA
Summary authors & editors: David Bowler

Do you think these clouds are the result of a secret government program with extraterrestrials? Of course not, these eerie clouds are called mammatus and occasionally occur during severe weather events. This magnificent formation formed on the west-side of a particularly strong thunderstorm cell that struck southern Maryland on May 10, 2000. The cell produced one-inch rainfall and spotty hail. With the sun setting in the western sky, the illumination was as awesome as the clouds themselves.

Mammatus often form below cumulonimbus clouds (those big, threatening, mushroom-like clouds) when cool, moist air sinks into a warmer environment. So while these clouds may seem alien to you, trust me, you need only worry about the hail, tornadoes, and gusty winds that might accompany our strange friend, the mammatus.

Related Links:

• The Formation of Mammatus Clouds
• University of CA Cloud Images
• Devilish Mammatus
• Fog and Weather
• Weatherpix: Severe Weather Photography
• Mike Umscheid's Storm Chase Photo Gallery
• More Mammatus
• University of CA, Berkeley, Cloud Images
• Australian Severe Weather Association Photo Hall of Fame
• Gary Peek's Photo Gallery
• More Cloud Images