Energy Conversions in the Atmosphere on the Scale of the General Circulation

Abstract

From the equations of balance established for the different forms of energy (potential, kinetic and internal energies), the energy fluxes, the rates of energy production and conversion are deduced. Provided weighted mean values are considered the zonally averaged value of the kinetic energy may be decomposed into kinetic energy of the mean motion and the mean kinetic energy of the large-scale eddies. The corresponding equations of balance are established. The axial symmetry with respect to the earth's axis allows the introduction of the kinetic energy of the zonal motion and of the motion in the meridional planes. Their equations of balance are given. The conversions between the different species of mechanical energies are envisaged and the influence of the inertial stability on the conversion of “meridional” eddy-kinetic energy into “zonal” eddy-kinetic energy is pointed out. The definition of the large-scale eddy diffusion of heat is deduced from the first law of thermodynamics. This definition contains the flux of ≥sensible heat≤ and of ≥latent heat≤ as an approximation. Neglecting viscosity and small-scale turbulence, the general formulas are applied to the large atmospheric disturbances. A tentative formulation of the second law of thermodynamics is given.