Abstract: The characteristics of the refraction of inertial gravity waves in the atmosphere with non uniform stratification and shearing basic flow have been studied in this paper based on Whitham's ray theory. A so-called environmental stability vector which is of crucial importance to the refraction of the gravity waves has been defined. It is the combination of the gradients of the environmental parameters:N²(static stability) ,ζ_a (inertial stability) and U_z (related to che baroclinic stability of the basic flow). The results show that the local wave energy guide is oriented to a direction normal to the vector . Regions of transition from a center of stability (stable or unstable) to another are the favorable passageway for the gravity wave energy.