Mammatus (also called mamma[1] or mammatocumulus, meaning "mammary cloud") is a cellular pattern of pouches hanging underneath the base of a cloud, typically a cumulonimbus raincloud, although they may be attached to other classes of parent clouds. The name mammatus is derived from the Latin mamma (meaning "udder" or "breast").
According to the WMO International Cloud Atlas, mamma is a cloud supplementary feature rather than a genus, species or variety of cloud. The distinct "lumpy" undersides are formed by cold air sinking down to form the pockets contrary to the puffs of clouds rising through the convection of warm air. These formations were first described in 1894 by William Clement Ley.[1][2][3]
- ^ a b Schultz, David M.; Hancock, Y. (2016). "Contrail lobes or mamma? The importance of correct terminology" (PDF). Weather. 71 (8): 203. Bibcode:2016Wthr...71..203S. doi:10.1002/wea.2765.
- ^ Anonymous (1975). International Cloud Atlas. Volume I. Manual on the observation of clouds and other Meteors (PDF). World Meteorological Organization. Archived from the original (PDF) on 2017-07-08. Retrieved 2017-05-13.
- ^ Ley, William Clement (1894). Cloudland: A study on the structure and characters of clouds. London, England: Edward Stanford. pp. 104–105.