Model of oscillatory instability in vertically-homogeneous atmosphere

摘要

Existence and repeatability of tornadoes could be straightforwardly explainedif there existed instability, responsible for their formation.However, it is well known that convection is the only instability in initiallystable air, and the usual convective instability is not applicable for these phenomena.In the present paper we describe an instability in the atmosphere, which can beresponsible for intense vortices.This instability appears in a fluid with Coriolis force and dissipation and hasoscillatory behaviour, where theamplitude growth is accompanied by oscillations with frequency comparable tothe growth rate of the instability.In the paper, both analytical analysis of the linear phase of the instabilityand nonlinear simulation of the developed stage of the air motion areaddressed.This work was supported by the RFBR grant no. 09-05-00374-a.