  Long's equation describes two dimensional stratified atmospheric flow over
terrain which is represented by the geometry of the domain. The solutions of
this equation over simple topography were investigated analytically and
numerically by many authors. In this paper we derive a new terrain following
formulation of this equation which incorporates the terrain as part of the
differential equation rather than the geometry of the domain. This leads to new
analytic insights about the solutions of this equation and enable us to compute
steady state gravity wave patterns over complex topography.
