The shape of averaged drop size distributions

Abstract

The shape of averaged drop size distributions (DSD) is studied from a large sample of data (892 h) collected at several sites of various latitudes. The results show that neither the hypothesis of an exponential distribution to represent rainfall with a high rain rate (R) nor the concept of equilibrium distribution arising from the various models using the parameterization of Low and List is compatible with the observations. To describe the DSD two regions have to be distinguished: a small-drop region, for diameter D smaller than a threshold Dc, and a large-drop region, for diameter D larger than Dc. For D < Dc the distributions are strongly dependent on R and on z0, the height of fall of the rain from the base of the melting level. -from Authors