Numerical Experiments on the Relation between Microphysics and Dynamics in Cumulus Convection.

by Francis W. Murray, Lloyd Randall Koenig

Purchase Print Copy

 FormatList Price Price
Add to Cart Paperback54 pages $20.00 $16.00 20% Web Discount

A previous numerical model of cumulus growth that treated condensation but not precipitation is modified by the addition of a parameterized treatment of liquid-phase microphysics. This modification improves the realism of the results for several parameters, including maximum height of cloud growth, maximum liquid content, amount and distribution of temperature departure, cloud shape, and occurrence and strength of subcloud downdraft. It is found that one of the most important controlling features in cloud growth is the rate of evaporation of droplets. In particular, the introduction of a class of large particles with a relatively slow evaporation rate produces a smaller temperature deficit at the cloud summit, hence more vigorous cloud growth. In this model, the upper and lower parts of the cloud are, to a large extent, decoupled dynamically; the development of a strong subcloud downdraft by evaporation of precipitation has little effect on the ultimate extent of cloud growth. 54 pp. Ref. (Author)

This report is part of the RAND Corporation Report series. The report was a product of the RAND Corporation from 1948 to 1993 that represented the principal publication documenting and transmitting RAND's major research findings and final research.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.