Stability of Thin Non-Rotating Hadley Circulations

Abstract

A simple parallel flow model is derived for a thin (depth to length ratio ?1) Hadley circulation in a two-dimensional box with rigid horizontal boundaries maintained at a temperature which increases linearly with the horizontal coordinate x. Vertical velocities are assumed to he confined to narrow regions near the ends. The stability of this solution is discussed. Several modes of energy transfer to and from the mean kinetic and potential energies exist. As opposed to the case of thermal convection between isothermal plates in a constant shear, transverse disturbances with symmetry normal to the shear vector are always more unstable than longitudinal disturbances with symmetry parallel to the shear vector. Implications of these results for recent theoretical ideas on the Venusian circulation are discussed.