Vortex Motion Driven by Differential Diffusion

Abstract

Convection induced by double (differential) diffusion in a rotating medium can generally lead to the transfer of vorticity and, in particular, to its concentration. In geophysical applications, this situation is not usually considered because the spatial and temporal scales of such convection and of rotation effects differ significantly: the period of planetary rotation is many orders of magnitude greater than the characteristic lifetime of the corresponding convective structures in seawater. Attention is given to the fact that there can be some processes in the atmosphere in which a noticeable vorticity transfer caused by a difference in the effective exchange coefficients for various substances seems to be more real. The effects of a double-diffusion-type in the air are in principle possible because of a difference in the rates of transfer of heat, water vapor, and/or heavy admixture. The simplest linear model of convection driven by double diffusion in a rotating medium is considered here. The possibility of a contribution of such effects to the concentration of vorticity during tornado formation is discussed.