The tidal motions in the atmosphere, which originate at stratospheric levels with the absorption of solar radiation by water vapor and by ozone, propagate upward through the mesosphere and dissipate in the thermosphere. They transfer heat and momentum (acceleration of the mean flow) into the region. the tidal motions are detected at mesospheric and thermospheric levels (50 to 120km in altitude) by the doppler shift of the airglow emission lines, by meteor scatter radars, and by incoherent scatter radars. This award is for a theoretical modelling effort to include the tides in a numerical general circulation model of the atmosphere running on the Cray computer at the National Center for Atmospheric Research in Boulder, CO. The results of several coordinated observational campaigns on the Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) will be interpreted in comparison with the model.