Accession Number : AD0649967

Title :   NUMERICAL SIMULATION OF THE EVOLUTION OF CUMULUS TOWERS,

Corporate Author : DOUGLAS AIRCRAFT CO INC SANTA MONICA CALIF MISSILE AND SPACE SYSTEMS DIV

Personal Author(s) : Murray,F. W. ; Anderson,C. E.

Report Date : OCT 1965

Pagination or Media Count : 105

Abstract : A numerical model for moist atmospheric thermal convection on the cumulus scale is developed and solved on a digital computer. The Boussinesq approximation and reversible thermodynamic processes are assumed. The momentum equation is solved in the Eulerian sense, but a quasi-Lagrangian scheme is used for the temperature and moisture equations. With the assumption of realistic initial temperature and moisture distributions and an initial perturbation of temperature (corresponding to solar heating) to trigger the mechanism, model clouds are grown whose features are compared with those of other types of models or of clouds in nature. Results show that if conditions of humidity and lapse rate are favorable a swelling cumulus will grow into a towering cumulus by vertical stretching of the convective cell, the resulting circulation bearing some resemblance to a ring vortex. When the cell penetrates into a layer with strong static stability and little moisture, the cell diminishes in size and strength, and an oscillatory regime is established. A form of large-scale entrainment is permitted by the model with the result that the mature cloud takes on a mushroom-like shape. The height of the base and top of the model cloud agree well with predictions from the parcel method. (Author)

Descriptors :   (*CUMULUS CLOUDS, *CONVECTION(ATMOSPHERIC)), MOISTURE, NUMERICAL ANALYSIS, SIMULATION, ATMOSPHERIC TEMPERATURE, STABILITY

Subject Categories : Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE