The linear theory for stationary Rossby waves excited by flow over long ridges is reviewed. The traditional “textbook” model, in which there is no disturbance of the potential temperature surfaces or streamlines upstream of the ridge, is shown to be inadequate. For both the β-plane and the f-plane cases, pressure forces cause lifting of the isentropes and a cyclonic turning of the streamlines upstream of the ridge. The β-plane and f-plane solutions are, however, totally different for long ridges owing to the resonant excitation of stationary Rossby waves and the vertical propagation of the long-wave components in the β-plane case. Curiously, the vertical displacement of the isentropic surfaces is nearly identical in the β-plane and f-plane solutions in the lower troposphere where the response is dominated by the short-wave vertically decaying components.

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