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Tornadoes and other atmospheric vorticesThe growth of random vortices in an atmosphere with buoyant instability and vertical wind shear is studied along with the velocities in a single gravity-driven vortex; a frictionless adiabatic model which is supported by laboratory experiments is first considered. The effects of axial drag, heat transfer, and precipitation-induced downdrafts are then calculated. Heat transfer and axial drag tend to have stabilizing effects; they reduce the downdrafts of updrafts due to buoyancy. It is found that downdrafts or tornadic magnitude might occur in negatively-buoyant columns. The radial-inflow velocity required to maintain a given maximum tangential velocity in a tornado is determined by using a turbulent vortex model. Conditions under which radial-inflow velocities become sufficiently large to produce tangential velocities of tornadic magnitude are determined. The radial velocities in the outer regions, as well as the tangential velocities in the inner regions may be large enough to cause damage. The surface boundary layer, which is a region where large radial inflows can occur, is studied, and the thickness of the radial-inflow friction layer is estimated. A tornado model which involves a rotating parent cloud, as well as buoyancy and precipitation effects, is discussed.
Document ID
19760023670
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Deissler, R. G. (NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 3, 2013
Publication Date
January 1, 1976
Subject Category
Meteorology And Climatology
Report/Patent Number
NASA-TM-X-73466
E-8813
Meeting Information
Meeting: Natl. Heat Transfer Conf.
Location: St. Louis, MO
Country: United States
Start Date: August 9, 1976
End Date: August 11, 1976
Sponsors: Am. Soc. of Mech. Engr., Am. Inst. of Chem. Engr.
Accession Number
76N30758
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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