Abstract: Problems of instability of rotating atmospheric motions are investigated by using nonlinear governing equations and the variational principle. The method suggested in this paper is Universal for obtaining criteria of instability in ail models with all possible basic flows. For example, the model can be barotropic or baroclinic, layered or continuous, quasi-geostrophic or primitive equations! the basic flow can be zonal or nonzonal, steady or unsteady.Although the basic flows show a great deal of variety, th...