[en] A rotating stratified two-dimensional fluid is considered in the ageostrophic stationary linearized version. In a previous paper it has been already studied, in Fourier transform, the resulting fourth-order partial differential equation for the stream function, and the response for a perturbing orography at ground level has been given. Now the more difficult study of the Green's functions as functions also of the vertical depth z of the atmosphere is undertaken. The result is that the net asymmetry found at the ground level between the waves downstream and the absence of waves upstream become less evident at higher levels of the atmosphere: the intensity of waves decrease with z and the waves slightly propagate also upstream