The non-linear equations describing adiabatic, quasi-static flow of stably stratified air over a mountain ridge on the rotating f- plane are integrated numerically in time, using potential temperature as vertical coordinate. The initial state is a horizontal, parallel flow over level ground, and the cosine-shaped, 400 km wide ridge, oriented normal to the initial flow, is allowed to grow to full height in 20 h. The potential vorticity remains constant in each isentropic surface, and this condition is used in the calculations instead of the mass continuity equation. Results of calculations starting with 4 different initial wind profiles are shown. After about 5 model days of integration, the motion within the integration area of length 4 Mm settled down to a nearly steady flow. This flow exhibits a system of gravity-inertia lee waves with dominating wavelengths comparable to the mountain width. The prominent wavelengths seem in all calculations to be limited to waves shorter than the inertia wavelength at the lower boundary (for which the particle frequency equals the Coriolis parameter). The waves are discussed in the light of linear theory and ray tracing. In a case where the initial wind velocity decreases with height, there is a clear tendency towards formation of pure horizontal, undamped inertia waves in the layer of wind shear, with cycloid-shaped horizontal trajectories. Besides the wave pattern, the stationary flow also shows a large-scale turning of the streamlines, to the left on the upstream side and to the right on the lee side, with a distinct anticyclonic bend over the mountain ridge. The formation of this turning is explained as a consequence of the loss of mass through the open boundaries connected with the growth of the mountain; thus the turning depends on the formulation of the inflow and outflow boundary conditions. Unless the large-scale turning is strictly symmetric with respect to the mountain ridge, the flow will possess a component along the ridge, with a corresponding geostrophic pressure gradient which together with the wave drag will contribute to the total horizontal force acting on the mountain. DOI: 10.1111/j.1600-0870.1984.tb00237.x