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Numerical simulations showing the role of the downdraught in cumulonimbus motion and splitting
Author(s) -
Thorpe Alan J.,
Miller Martin J.
Publication year - 1978
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49710444203
Subject(s) - inflow , outflow , storm , relative motion , wedge (geometry) , forcing (mathematics) , wind shear , environmental science , geology , meteorology , mechanics , atmospheric sciences , wind speed , physics , geometry , mathematics
The results of two numerical simulations are presented. The first shows the classic deviatory motion of a multicell system, to the right of the mean tropospheric wind. The second, having a more highly sheared environment, produces a storm which splits into two after the formation of a wedge‐shaped downdraught outflow. Both simulations highlight the important role played by the downdraught dynamics in establishing a regenerative forcing mechanism. In the higher shear case the updraught core exhibits a large downshear slope with rain falling into the inflow region, thus producing a split updraught core and eventually two distinct cells. The strength and direction of the relative inflow lead to the different structures and life histories of the two storm systems. The importance of the flow relative to the cell is demonstrated by considering the effects of Galilean transformations of the coordinate system.