SIMPLIFIED DYNAMICS OF SHALLOW BAROCLINIC ATMOSPHERE

Simplified equations of for perturbations of horizontally baroclinic a tmosphere are obtained. Perturbations are of synoptical scales with fr equencies lower than Coriolis one, so that geostrophic approximation i s valid. Exact nonlinear solutions of these equations in the form of d ipole vortex is found. It is shown that contrary to the barotropic cas e the baroclinic vortex can translate with velocities lower than the R ossby velocity. Nonlinear stage of the baroclinic instability is simul ated numerically for the atmosphere with large-scale gradients of pres sure and potential temperature.