We find that certain features of the response of the high-latitude thermosphere to inputs of energy and momentum can be explained qualitatively in terms of the theory of geostrophic adjustment. The theory is well known in the fields of oceanography and meteorology. The adjustment process is critically dependent on the ratio of the scale size of the forcing to the Rossby radius of deformation, a natural parameter of the mean atmospheric state. When the ratio is small, large wind speeds are efficiently generated by a momentum source. When the ratio is large, changes in the mass field associated with a heat source are more effectively produced. The variation of the Rossby radius with height explains the qualitatively different responses of the high-latitude E and F regions during disturbed geomagnetic conditions as shown by both observations and numerical models. The E region is a more efficient generator of large winds, whereas the F region creates perturbations equally well in the mass field and the wind field. Earlier results by Dickinson et al. (1971) and Volland and Mayr (1971) are explained in terms of geostrophic adjustment, and the analytic solutions are also compared to the results of the integration of the spectral numerical model of Mayr and Harris (1978). We find that the analytic solutions are in good agreement with the model results regarding the apportionment of energy between the divergent and rotational components of the wind field as a function of wavenumber.