Accession Number : AD0625689

Title :   RELATIONSHIPS BETWEEN TROPICAL PRECIPITATION AND KINEMATIC CLOUD MODELS.

Descriptive Note : Progress rept. no. 8, 15 Feb-15 Aug 65,

Corporate Author : TRAVELERS RESEARCH CENTER INC HARTFORD CT

Personal Author(s) : Arnason, Geirmundur ; Newburg, Edward A.

Report Date : JAN 1966

Pagination or Media Count : 30

Abstract : Dry, shallow convection of the roll-type is simulated by means of numerical experiments. Initially, a buoyant bubble near the lower boundary is introduced into neutral surroundings, and the equations of motion, continuity, and thermodynamics are solved numerically to obtain the development in time of the bubble. The computed events show the bubble to rise at an accelerated rate and take the shape of a mushroom with a slim stem and a rounded top which is characterized by a concentration of isotherms. The associated toroidal circulation is that of a narrow intense updraft in the center, and a broad descending flow further out. The pressure field induced by the buoyant bubble is nonhydrostatic and, as such, is of particular interest. It creates inflow extending from the lower boundary to the core of the bubble and accelerates the inflowing air upwards along the stem. The pressure distribution is such that the bubble is exposed to a form drag similar to that on a body moving through a viscous fluid. The evolution of events spans a time period of twenty minutes. Near the end of this period, the bubble is approaching the upper boundary (3000m), the influence of which is becoming noticeable in the results. By then the initial temperature excess of 0.38C has diminished to 0.13C as a result of truncation errors of the finite difference scheme. It is concluded that the computed events are qualitatively in good agreement with observed behavior of dry convection in the atmosphere, and that the finite difference schemes that were used compensate to some degree for the neglected effects of friction and thermal diffusion in the system of physical equations used in the numerical experiment. (Author)

Descriptors :   *CONVECTION(ATMOSPHERIC), NUMERICAL ANALYSIS, TROPICAL REGIONS, RAINFALL, CLOUDS, MATHEMATICAL MODELS, CORRELATION.

Subject Categories : Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE