An Analysis of Cloud Drop Growth by Collection: Part I. Double Distributions

A new, highly accurate, yet fast method for the numerical solution of the stochastic collection equation is described. Basic size distribution parameters are defined that lay a basis for a parameterized description of stochastic collection. Application is made to double initial distributions. A newly defined mode, here designated “large hydrometeor self-collection”, is found to occupy an important position along with auto-conversion, accretion and breakup in the generalized description of drop growth by collection.