Dynamics of the Convective Rise of Thermals in the Atmosphere

Abstract

Exact and approximate relations have been obtained to describe the evolution of the following parameters of heated air parcels during their convective uplifting in the atmosphere: the altitude and temporal dependences of the speed of the parcel center, the parcel characteristic size (radius), and the excess relative temperature. Cases of moderate and strong heating have been considered. The original equations include relations for the rate of uplifting thermals, the mass of entrained cool air, and the complete integral of thermal buoyancy. It has been shown that during uplifting the radius of the heated air parcel increases, the excess temperature decreases, and the uplift rate varies nonmonotonically: first, it increases from zero and reaches a maximum; then it gradually decreases to zero. Numerical estimates for characteristic situations have been performed.