The World Distribution of Annual Precipitation Efficiency

Abstract Precipitation efficiency is the percentage of the total atmospheric water vapor above a station which is condensed and falls to earth as measurable precipitation on an average day. As such, it is an index of the effectiveness of dynamic precipitation mechanisms in a region and is a useful method of illustrating the degree of atmospheric stability. In this paper the concept of precipitation efficiency and its method of determination are discussed. An example covering the entire earth for the annual period is presented. The world map oi annual precipitation efficiency well illustrates the regions of pronounced dynamic stability and instability. The areas of highest precipitation efficiency are mid-latitude, windward coasts where orographic effects augment precipitation. Areas of lowest precipitation efficiency are the low-latitude deserts.