In a first step, the problem of inviscid axisymmetric flow with buoyancy is investigated. It is found that both supercritical and subcritical vortex flows depart from their critical flow states if they are dominated by buoyancy. In a second step, the effects of entrainment are also taken into account. However, the investigation is restricted to nearly self‐similar flows. Both supercritical and subcritical vortex flows approach their critical flow states if they are dominated by entrainment. However, the superimposed effects of buoyancy and entrainment may lead to an equilibrium close to the critical state. It is argued that the existence of such an equilibrium is the direct reason for the appearance of certain violent vortex flows in nature, including tornadoes and fire storms. The weather conditions that may lead to the appearance of tornadoes and the different forms of appearance are also discussed.

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© 1994 American Institute of Physics.
1994
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