An Analogy Between the Equatorial Easterlies and Supersonic Gas Flows

The almost complete mathematical analogy is established between incompressible flow of air under an inversion, and one- and two-dimensional flow of a compressible fluid at high speed. Some mathematical and graphical methods of determining one-dimensional flows are discussed and demonstrated. Since the tropical easterlies are often a one-dimensional current with an inversion, the techniques are theoretically applicable to them. The theory admits three types of disturbances oriented normal to the current: a rarefaction wave, a compression wave, and a jump. The mathematical theory is shown to conform with general practical and practiced tropical forecasting methods and to agree with specific examples.