We investigated the scale-dependent radiative damping of internal gravity waves on the limit of amplitude growth with height in the altitude region 60--120 km of the terrestrial planetary atmospheres. The radiative damping due to the CO2 15 &mgr;m radiation limits wave propagation much more effectively in the Mars atmosphere than in the Earth's atmosphere. Though radiative damping is as effective in the Venus atmosphere as in the Mars atmosphere at ~120 km altitude, it is not so effective below ~100 km altitude. The damping due to molecular diffusion is significant compared to radiative damping above ~80 km altitude on the Earth and above ~120 km altitude on Mars, whereas on Venus it is not significant even above ~120 km altitude. ¿ American Geophysical Union 1995