Model of oscillatory instability in vertically-homogeneous atmosphere

Abstract

Abstract. Existence and repeatability of tornadoes could be straightforwardly explained if there existed instability, responsible for their formation. However, it is well known that convection is the only instability in initially stable 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 be responsible for intense vortices. This instability appears in a fluid with Coriolis force and dissipation and has oscillatory behaviour, where the amplitude growth is accompanied by oscillations with frequency comparable to the growth rate of the instability. In the paper, both analytical analysis of the linear phase of the instability and nonlinear simulation of the developed stage of the air motion are addressed. This work was supported by the RFBR grant no. 09-05-00374-a.

Tornado-type stationary vortex with nonlinear term due to moisture transport

“…6-8). It is convenient to express velocity in terms of potential, toroidal, and poloidal fields (Rutkevich and Rutkevych, 2009):…”

“…Other non-linear terms have the same problem, since they do not introduce energy in the system. Renno and Ingersoll (1996) described convection in the atmosphere as a heat engine between warm surface (due to solar radiation) and cold troposhpere, this assumption implies heat accumulation and release by means of black-body radiation. However, continuous and powerful source of energy observed in tornadoes and cyclones has to come from a source much more efficient than the black body radiation or heat conductivity.…”