The envelope orography scheme developed by Wallace et. al.has been shown to improve medium-range weather forecasts of ECMWF. Their numerical experiment data are used for this research. Verifications include zonal mean westerly wind, temperature and meridional circulation, mean meridional flux of angular momentum due to meridional circulations and planetary and synoptic scale eddies. Results show that the introduction of this scheme improves predictions of zonal temperature and wind fields in tropical troposphere, and simulates better the total eddy angular momentum flux. However predictions of synoptic scale systems and parameterizations of tropical (Convection and culmulus friction have to be improved further.