This may be neglected however since it is order smaller than other terms such as . We shall call the equations resulting from these approximations the Anelastic, Quasi-Boussinesq set or
AQB equations i.e.
and
where the Coriolis force has been added to the momentum equation.
The relative simplicity and accuracy of these equations makes them ideal for studying meteorological flow dynamics and extensive use will be made of them in this book.
Finally, the following identity should be noted :
where the continuity equation (40) has been used. The right-hand side expression will be referred to as the flux form of the material derivative and will be used frequently to obtain global conservation laws.