We show that Alfven gravity waves propagating in a gravitationally stratifi
ed atmosphere do not suffer damping as a result of the rate of working of t
he gravity drift current on the electric field of the waves. A self-consist
ent treatment involving conservation of total energy, Poynting's theorem, a
nd the rate of working of the various drift currents on the electric field
demonstrates that dissipation only arises from "real" dissipative processes
such as ohmic heating or viscous effects; otherwise the system is adiabati
c. We also outline the propagation properties of coupled small-amplitude hy
dromagnetic gravity waves for the case of vertical and horizontal magnetic
fields. In the latter case we discuss the phenomenon of critical level abso
rption, which can take place where the horizontal wave phase speed matches
the Alfven speed at some height in the atmosphere.