BALANCED ATMOSPHERE-OCEAN DYNAMICS, GENERALIZED LIGHTHILL RADIATION, AND THE SLOW QUASI-MANIFOLD

Three of Lighthill's many interests, (a) wave propagation in moving me dia, (b) acoustic streaming and related phenomena, and (c), in a very subtle and fascinating way, aerodynamic sound generation, are all turn ing out to be fundamental to understanding our atmospheric environment . Among other things there is the global-scale circulation that shapes the ozone layer and controls the rate of destruction of man-made chlo rofluorocarbons (CFCs). Recent progress in this field is sketched, inc luding progress in understanding the abstract structure of Hamiltonian theories of balanced motion, the so-called slow ''manifold''. Here a generic phenomenon, ''velocity splitting'', turns out to be intimately related to aerodynamic sound generation, particularly its generalizat ion describing the spontaneous emission of inertia-gravity waves from unsteady vortical motions in stratified rotating flow.