The transfer function approach in terms of vector spherical harmonics is used to describe the thermospheric response to time dependent sores on the globe. The computations are carried out for frequencies from 0 to 140 cycles per day (c/d), corresponding to periods of almost 10 min; the horizontal wavelength resolution is about 200 km. In the transfer function, we can distinguish basically two kinds of waves, trapped and propagating ones. The trapped waves have the character of a low pass filter, i.e., the large scale and long term variations are preferentially excited. The propagating waves comprise the fundamental, quasi-horizontally propagating wave and the reflected andducted wave modes. These waves become important at frequencies above 3 c/d. Using the Fourier integral representation, impulsive perturbations are stimulated for source distributions on the globe. The following features characterize the thermospheric response: (1) The dynamic processes are most important during the energization phase. Winds then redistribute energy and mass globally. (2) The temperature and density perturbations remain for some time after the source has been turned off, heat conduction and diffusion accounting primarily for the slow decay. With decreasing source altitude the relaxation time-constant increases. (3) Propagating gravity waves are launched mainly when the source is abruptly turned on or off. The source frequency spectrum is then very broad and the waves are generated by ringing. Near the source, their pulse durations are typically on the order of 20 min and are determined, through the dispersion relation for gravity waves, by the horizontal dimension of the source (about 700 km). As the waves propagate away from the source, the longer periods (and wave lengths) become more important, consistent with classical gravity wave theory. (4) After the source is turned off, the atmospheric circulation reverses, exhibiting a global scale oscillation which is determined by the duration of the disturbance. (5) Outside the source region, the onset of the disturbance is delayed corresponding to horizontal signal velocities of about 800 m/s, near the local speed of sound. Due to reflection from the base of the thermosphere, a second signal is launched which propagates with a velocity of about 380 m/s. This wave, however, is rapidly attenuated. A weaker third signal is launched which propagates with a velocity of only 230 m/s and therefore dominates the response near the source region (high latitudes) some time after the onset of the disturbance. This is the ducted wave from the lower atmosphere, which is weakly attenuated and can travel large distances away from the source. (6) The time delays between the maxima in the temperature and densities are controlled by the time constants for heat conduction and diffusion (which can be relatively long), but are limited by the duration off the disturbance.