SHORT BAROCLINIC WAVES OF SMALL AMPLITUDE IN A MOIST ENVIRONMENT

Baroclinic instability at short wavelengths is investigated using a primitive-equation non-hydrostatic two-dimensional numerical model in which the vertical shear is uniform and in which moisture is present in the lower part of the troposphere. The height of the transition between saturated and unsaturated air determines the vertical and horizontal scales of the most unstable modes. As the transition region is raised the most unstable wavelength increases, until the large-scale (moist) Eady wave, extending to the tropopause, prevails