This book deals with the main principles of large-scale atmospheric dynamics on the basis of adiabatic motion constants. It can be considered as an introduction to the theory of quasi two-dimensional fluid motion concentrating primarily on nearly horizontal fluid parcel displacements in a stably stratified compressible fluid. A thorough mathematical treatment of the governing equations is coupled with a clear interpretation of the phenomena studied and accompanied by examples of real meteorological data analysis. Topics include a complete set of compressible fluid dynamic equations along with a survey on fluid dynamical conservation laws used in meteorology and atmospheric physics; the derivation of two-dimensional atmospheric models; large-scale flows; isentropic analysis of large-scale atmospheric processes; and the principles of kinetic energy sinks and their relation to the energy balance in the atmosphere.