# A Statistical Study of Cloud Droplet Growth by Condensation

- Helmut Weickmann

Published Online: 18 MAR 2013

DOI: 10.1029/GM005p0220

Copyright 1960 by the American Geophysical Union.

Book Title

## Physics of Precipitation: Proceedings of the Cloud Physics Conference, Woods Hole, Massachusetts, June 3-5, 1959

Additional Information

#### How to Cite

Rooth, C. (1960) A Statistical Study of Cloud Droplet Growth by Condensation, in Physics of Precipitation: Proceedings of the Cloud Physics Conference, Woods Hole, Massachusetts, June 3-5, 1959 (ed H. Weickmann), American Geophysical Union, Washington D. C.. doi: 10.1029/GM005p0220

#### Publication History

- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1960

#### ISBN Information

Print ISBN: 9780875900056

Online ISBN: 9781118668931

- Summary
- Chapter
- References

### Keywords:

- Behavior of microscale variables;
- Cloud droplet growth;
- Development of droplet spectrum;
- Droplet spectrum;
- Growth equation and basic integral constraint

### Summary

A droplet spectrum is defined in terms of the moments of its frequency distribution, and equations are derived for the rate of change of these moments. Effects of dissolved salt are not considered; this limits the application of the theory to regions well above cloud base. It is shown that the supersaturation adjusts itself towards a quasi-steady value within a time given by $C(N {\bar r})ˆ{−1} $ where *N* is the number of droplets per cm^{3}, ${\bar r}$ is the average droplet radius in cm, and *C* is a coefficient of size order one cm^{−2}. The basic parameter used to characterize the cloud development is the average growth rate of droplet mass. For very slow rates the droplet size spectrum has a tendency to widen, but at higher growth rates a contraction of the spectrum occurs. In the limit the linear width of the spectrum is inversely proportional to the average radius and the standardized form of the spectrum is invariant.