The modulation of convection by a lateral shear

Several aspects of thermal convection in the presence of a lateral shear as sociated with either a shear line [with velocity V(x)] or a circular vortex [with azimuthal velocity V(r)] are considered. Parameter settings that fav or suppression of convection near the axis of the shear Row or near the cen ter of a cyclonic vortex are determined by looking at the structure of the linear neutral modes at the onset of convection, or at the modes that have the largest growth rates at highly supercritical Rayleigh numbers where the motions are nearly inviscid. Both parallel [or axisymmetric (2D longitudin al)] and wavy for nonaxisymmetric (3D)] disturbances are considered, althou gh the analysis focuses on the former A weakly nonlinear amplitude equation shows that the bifurcation is supercritical, but even in the presence of v ertical asymmetry in the applied thermal mean gradient, there is nor a sign ificant preference for upwelling or downwelling at the axis. Within the con text of the linear model of convection in lateral shear, it is suggested th at strong atmospheric vortices may suppress thermal convection in their cor es. a mechanism possibly associated with vortex "eyes." A simple laboratory demonstration of the main result is included.