Response of a bounded atmosphere to a non-resonant excitation

The response of a bounded atmosphere to a non-resonant excitation applied at its basis is studied. It is shown that the essential feature related to this kind of excitation is that the distribution of the energy of the velocity field relatively to the frequency and horizontal wavelength is a function of height and merely depends on the structure of the atmosphere above the level at which it is considered. The preliminary results concerning an isothermal atmosphere are presented and their relevance to the solar case is discussed.