Jule Charney, more than any other living figure, has guided the postwar evolution of modern meteorology. His scientific work has had dramatic impact in a number of areas. In his early work he showed how cyclones draw their energy from larger-scale atmospheric nows. This work was the result of his doctoral studies at UCLA, under the guidance of J. Bjerknes, and his research in his first postdoctoral years. Here he showed the great physical insight that has characterized his entire career, namely, the ability to distill from among the complex interactions which characterize the atmosphere those relatively few ingredients that permit the construction of simplified models that still have a strong relevance to natural phenomena.