Stratus cloud supersaturations

Abstract

A wide range of California coastal stratus cloud droplet concentrations (N c) were compared with CCN spectra to provide numerous estimates of cloud supersaturations (S). These revealed the predicted decrease of S with higher CCN concentrations (N CCN). A significant result was frequent stratus cloud S significantly above 0.3%, especially for more maritime N CCN and N c (i.e., <300 cm -3). This means that much smaller and more numerous particles than previously considered interact with the most important clouds for the indirect aerosol effect. © 2010 by the American Geophysical Union.