PRODUCTION OF TURBULENCE IN THE VICINITY OF CRITICAL LEVELS FOR INTERNAL GRAVITY WAVES.

Calculations demonstrating that internal gravity waves become unstable in the vicinity of critical levels are reported. An analytic linear inviscid model is used to look at the geometry of these unstable regions using parameters appropriate to the atmosphere. A nonlinear model is used to establish the usefulness of the simple analytic model. Observational evidence is cited indicating that the production of turbulence near critical levels might be of importance in the planetary boundary layer, in the upper troposphere and stratosphere, in the mesosphere and lower thermosphere, and even in the oceans.