A Quasi-One-Dimensional Cumulus Cloud Model and Parameterization of Cumulus Heating and Mixing Effects.
Abstract
The characteristics properties of cumulus convection are investigated using a semi-one-dimensional axisymmetric quasi-Lagrangian steady state model which takes into consideration the influences of the pressure perturbation, density stratification and nearby moist downdraft under two different environmental situations, namely, 1) a potentially more unstable tropical environment and 2) a less unstable middle latitude environment with prominent stable layers in middle troposphere. It is found that the compressional heating of the dry environment makes the cloud air warmer and reduces the updraft velocity slightly and moist downdraft cools the cloud air and reduces both the updraft and the cloud depth, while the influence of pressure perturbation is also to reduce the updraft but it is effective only for clouds of radii larger than 1000 m. The influence of density stratification is to reduce w sub c slightly at low levels and augment w sub c at high levels and to slightly increase the cloud depth. The calculated precipitation rates appear to be close to the representative values obtained from observations. One most interesting result given by the model is that, under the less unstable middle latitude environment, the precipitation rate jumps from lower than .7 cm/hr for cloud radii smaller than 1000 m to more than 5.4 cm/hr for cloud radii greater than 2000 m, reflecting the inhibiting effect of the mid-troposheric stable layer on the penetrative power of the smaller clouds.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1979
- Accession Number
- ADA083024
Entities
People
- H. L. Kuo
- W. H. Raymond
Organizations
- University of Chicago