*) This is a brief summary of Dr. Bergeron's eventual monograph in German in Geofysiske Publ., and is a revision of his paper read to the Edinburgh meeting of the U. G. G. I. meteorology section in 1936 and issued at that time in lithoprint; it has also been published in German in Zts. f. angew. Met., Dec., 1936, pp. 381–95 (repr. as Communications: Series of papers, no. 13, Statens Met.-Hyd. Anst., Stockholm, 1937). —Ed.