The Exploration of Certain Features of Tornado Dynamics Using a Laboratory Model

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  • 1 National Severe Storms Laboratory, NOAA, Norman, Okla. 73069
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Abstract

Three characteristic features of tornadoes are simulated in a laboratory system and the associated flow is observed and discussed. These are (i) a characteristic surface pressure profile, (ii) a bulging deformation on the vortex core, and (iii) multiple vortices in a single convergence system. Vortex motion is very sensitive to the geometrical features of the larger flow in which it is imbedded. Only when the diameter of the updraft column exceeds the depth of the inflow layer can features (i) and (iii) be produced in the present model. When the updraft diameter is large compared to the depth of inflow, inertial effects associated with large changes in radial momentum produce significant convergent forces. When the updraft diameter is small compared to depth of inflow layer, the inflow speed is relatively small and related inertial effects are small. It is concluded that radial momentum flux is an important factor in the production of atmospheric vortices.

Abstract

Three characteristic features of tornadoes are simulated in a laboratory system and the associated flow is observed and discussed. These are (i) a characteristic surface pressure profile, (ii) a bulging deformation on the vortex core, and (iii) multiple vortices in a single convergence system. Vortex motion is very sensitive to the geometrical features of the larger flow in which it is imbedded. Only when the diameter of the updraft column exceeds the depth of the inflow layer can features (i) and (iii) be produced in the present model. When the updraft diameter is large compared to the depth of inflow, inertial effects associated with large changes in radial momentum produce significant convergent forces. When the updraft diameter is small compared to depth of inflow layer, the inflow speed is relatively small and related inertial effects are small. It is concluded that radial momentum flux is an important factor in the production of atmospheric vortices.

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