two air masses of different density, to its death as an occluded cyclone. Complex structures may now be identified from relatively sparse data. No such synoptic models had been evolved for tropical disturbances. It was not until observation stations were established throughout the tiny islands of the South Pacific, that a comprehensive picture could be obtained, unobscured by continental influences or local diurnal effects. Meteorologists in the forward areas were too busy to make much immediate contribution to the broad theoretical aspects. However, in 1943, C. E. Palmer (N.Z. Meteorological Service) was invited to take charge of the Institute of Tropical Meteorology being established at San Juan (Puerto Rico) as a joint project of the U.S.A.A.F., U.S.N. and U.S. Weather Bureau for research Fig. 1.—Example of routine wind flow analysis in tropics.