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Centre for Atmospheric Science

Past speakers and topics-Mammatus

Centre for Atmospheric Science Seminar Thursday 31 May 2007

Prof. David Schultz
University of Helsinki, and Finnish Meteorological Institute, Helsinki, Finland (On leave from the University of Oklahoma, and NOAA National Severe Storms Laboratory, Norman, Oklahoma, USA)

Mammatus are an intriguing enigma of atmospheric fluid dynamics and cloud physics. Most commonly observed on the underside of cumulonimbus anvils, mamma- tus also occur on the underside of cirrus, cirrocumulus, altocumulus, altostratus, and stratocumulus, as well as in contrails from jet aircraft and pyrocumulus ash clouds from volcanic eruptions. Despite their aesthetic appearance, mammatus have been the subject of few quantitative research studies. Observations of mammatus have been obtained largely through serendipitous opportunities with a single observing system (e.g., aircraft penetrations, visual observations, lidar, radar) or tangential observations from field programs with other objectives. Theories describing mammatus remain untested as adequate measurements for validation do not exist because of the small distance scales and short time scales of mammatus. Modeling studies of mammatus are virtually nonexistent. As a result, relatively little is known about the environment, formation mechanisms, properties, microphysics, and dynamics of mammatus.
This talk presents a review of mammatus that addresses these mysteries. Pre- vious observations of mammatus and proposed formation mechanisms are discussed.
Idealized cloud-modeling studies of mammatus are presented, believed to be the first ever to model mammatus explicitly. Finally, because much still remains to be learned, research opportunities are described for using mammatus as a window into the microphysical, turbulent, and dynamical processes occurring on the underside of clouds.