Number densities of N2, O, Ar, and He at a height of 280 km, derived from measurements made with the gas analyzer aboard the polar-orbiting satellite Esro 4, were subjected to a preliminary analysis to establish a global pattern for variations that accompany geomagnetically induced disturbances. At middle and high latitudes, during periods of sustained geomagnetic activity, the number densities of N2 and Ar display regular 24-hour variations in phase with the variations of geomagnetic latitude caused by the earth's rotation under the satellite orbit; O and He display the same 24-hour variations with an opposite phase. These variations can be quantitatively explained by assuming that the temperature increases with geomagnetic latitude and that a change in the temperature T is accompanied by a change in the height of the homopause, zH. During such periods of sustained activity, dzH/dT is of the order of 50--60 m/¿K, and the maximum temperature is reached near the magnetic pole. During transient magnetic storms, at higher latitudes, the 24-hour variations with geomagnetic latitude are swamped by those roughly in phase (N2 and Ar) or in antiphase (He) with Kp during the storm, O densities vary but little, almost erratically. Here, too, the observations are well represented by the previous assumption about the homopause, except that we need a smaller value of dzH/dT, about 30 m/¿K. From this and other evidence it appears that the homopause reacts slowly to geomagnetic activity, reaching a steady state height level only after 2 or 3 days. There is good indication that the maximum temperature during transient storms is shifted toward the auroral zones. An entirely different regime prevails in the equatorial region during magnetic storms. There all four atmospheric constituents vary in phase and with similar amplitudes, following the variations of Kp with a lag of about 8 hours. Since the lag is much smaller at higher latitudes, this finding suggests a density wave proceeding from higher latitudes.