Mammatus (also known as mamma or mammatocumulus, meaning "breast-cloud") is a meteorological term applied to a cellular pattern of pouches hanging underneath the base of a cloud. The name "mammatus" is derived from the Latin mamma (breast), due to the resemblance between the shape of these clouds and human female breasts. Mammatus are most often found on the anvil cloud that extends from a cumulonimbus, and therefore are commonly associated with severe weather.

Recently selected pictures: Von Kármán vortex street, Crepuscular rays, Cumulonimbus cloud, More...