An analysis of density meaurements of Ar, N2, O, and He made at 280 km with the gas analyzer aboard the polar-orbiting satellite Esro 4 has yielded a global model of the variations in temperature, density, and composition that occur in the disturbed thermosphere. In the model the increase of temperature over quiet conditions in a nonlinear function of the planetary geomagnetic index Kp; its latitude profile is approximated by a sin4&PHgr; law, where &PHgr; is the 'invariant' magnetic latitude. A density wave proceeding from high latitudes is approximated by a cos4&PHgr; law. A strong nonlinearity in the relation between the temperature variations and the variations in the height of the homopause explains a previously found behavioral diffrence in the variation of atomic oxygen during magnetic storms and during periods of sustained geomagnetic activity.