Oslo, Dybwad, 1929. Orig. printed wrappers. "Avhandlinger utgitt av Det Norske Videnskaps-Akademi". Matem.-Naturvid. Klasse, 1929. No. 7. 29 pp.
First edition by one of the true pioneers of meteorology, often called "the father of modern meteorology". According to Arnt Eliassen, "He (Bjerknes) put forward the view that weather forecasting should be dealt with as an initial value problem of mathematical physics and carried out by numerical or graphical integration of the governing equations. This is nothing more than treating the atmosphere as a physical system, but at the time it was a revolutionary idea."