This book presents new research on the mathematical description of tsunamis and hurricanes. The description includes dissipative terms and does not contain singularities or two valued functions. The book uses the equivalence principle of solutions of nonlinear large gas dynamic waves and of solutions of water wave equations. An extension of the continuity equation by a source term due to evaporation rates of salt seawater help to understand hurricanes. Detailed formula, tables, and results of the calculations are given.