* Essential excerpts from a longer paper of the same title read to the American Physical Society meeting at Denver June 26, 1937 at a Symposium on Cosmic Physics and High Altitude Effects; the full paper will appear in the Journ. of Applied Physics. This article reiterates substantially the same remarks made by Prof. Willett at the Washington meeting of the Amer. Met'l. Soc., April, 1937, under the title “Analysis of Northern Hemisphere Weather Maps For the Winter of 1936–37”, which will also be published in the Trans. Amer. Geophys. Union, 1937.