Mammatus Clouds Over England
June 13, 2003
The above photo was taken on May 19, 2003, over Oxfordshire, U.K. (central England) and shows a beautiful example of mammatus clouds. These pendulous clouds are obviously named for their udder-like appearance. They typically form as a result of cold downdrafts within mature thunderstorm cells -- cold air essentially punches pouch-like shapes into the base of the cloud. Although they're sometimes associated with severe storms and hail, more often than not, their looks are more menacing than the weather they produce.
This photo was captured with a Canon S30 digital camera (1/125 f4).