Aerosol effects on Clouds and Precipitation: Buffered states, runaway states, and self-organization

February 25, 2010

Graham Feingold

Hosted by Bill Cotton

Abstract

It has been hypothesized that changes in the concentration of the aerosol can alter precipitation processes, change cloud lifetime and hence the radiative forcing of the climate system. Despite decades of research, it has proven frustratingly difficult to establish climatically meaningful relationships among aerosol, clouds, and precipitation. As a result the climatic effect of aerosol remains controversial. In this talk it will be argued that the difficulty in untangling relationships between aerosol, clouds, and precipitation is largely a consequence of the system frequently being in a buffered, or self-regulating state. Examples of buffering will be presented along with a counter example of a "runaway" aerosol effect on clouds and the resulting self-organizing properties of the cloud system.