Tor Harold Percival Bergeron

This lecture memorializes the life and scientific career of Tor Harold Percival Bergeron, one of the founders of modern meteorology. It contains a brief account of his life and remarkable personality. Mainly, it presents, in chronological sequence, his more important scientific contributions to meteorology, including his (together with G. Swoboda) analysis of the development of the Skagerrak storm cyclone of Oct. 14-15, 1923, on the basis of the polar front theory, which was published in 1924; his dissertation (1928), which stressed the need for three-dimensional weather analysis, i.e., the need for aerological analysis in contrast to frontal analysis, and demonstrated that weather analysis for daily weather forecasts is concerned with the definition of cold and warm air masses on the basis of relatively unchanging characteristics; the development of the precipitation theory, involving the postulation that almost every real raindrop and all snowflakes originated around an ice crystal; the paper on the mechanism of abundant precipitation (1949) in which was stated the importance of the joint effect of two factors, i.e., intensive condensation and effective release of precipitation, and the existence of two different cloud systems for such precipitation--one, the seat of the ice crystal formation, termed the seeder cloud, and the other, located below the 500-700-mb level, the condenser or spender cloud; the compilation of the cloud atlas; the pioneering idea of drought relief in the Tropics by manipulating the moisture flux far upward of the drought area; his interest in the Greenland Ice Cap; and the organization of Project Pluvius, involving the study of the mesometeorological characteristics of areal precipitation.