Deep gravity waves in moist-saturated atmospheric air

The equations of motion of a moist saturated, dissipative, stratified atmos phere are used in the case of small Schmidt number, to describe the propaga tion of linearized gravity waves in deep cloudy atmosphere : as in dry air, the consequence of the dissipation is the diffusion and the damping of wav es through the medium. However. there exist particular cases of stratificat ion, for which the moisture gives rise at locally undamped waves. This prop erty justifies the existence of oscillatory unstable regimes when we study shallow convection in the medium.