A PROPOSED MECHANISM FOR CUMULONIMBUS PERSISTENCE IN THE PRESENCE OF STRONG VERTICAL SHEAR

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  • 1 Naval Postgraduate School, Monterey, Calif.
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Abstract

Based on observations that vigorous convective elements in the atmosphere act as obstacles to the environmental flow, it is shown that hydrodynamic pressures exist near the strong updraft. After utilizing this result, a simple model of a quasi-steady-state cumulonimbus is proposed. It is then found that vertical shear in unidirectional environmental flow leads to enhanced vertical motions on the perimeter of the updraft. These intensified vertical motions would allow the updraft to be less adversely affected by the shearing forces and may explain the persistence or growth of such storms.

The research reported here was principally conducted while the author was a graduate student of the Department of Atmospheric Science of the University of Missouri, and a portion was included in the author's Ph. D. dissertation.

Abstract

Based on observations that vigorous convective elements in the atmosphere act as obstacles to the environmental flow, it is shown that hydrodynamic pressures exist near the strong updraft. After utilizing this result, a simple model of a quasi-steady-state cumulonimbus is proposed. It is then found that vertical shear in unidirectional environmental flow leads to enhanced vertical motions on the perimeter of the updraft. These intensified vertical motions would allow the updraft to be less adversely affected by the shearing forces and may explain the persistence or growth of such storms.

The research reported here was principally conducted while the author was a graduate student of the Department of Atmospheric Science of the University of Missouri, and a portion was included in the author's Ph. D. dissertation.

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