Abstract: With linear two-layer model the development and movement of long waves in the upper and lower part of the troposphere are studied. The main results are:1. The usually used synoptic rules-the disturbance develops, when the pressure wave preceeds the temperature wave-is valid only in upper troposphere for ultra-long waves (with wave ength of about 104 km or larger); valid from middle troposphere upward for long waves of wave length of about 7000 km and valid for whole troposphere for long wave of comparatively shorter wave length.2. In the basic current with shear ,the upper part of the disturbance develops while the lower part,damps when the axis of the trough or ridge line tilts westward with height and the upper part of the disturbance damps while lower part develops when the axis tilts eastward with height. When the upper and lower part develop or damp simultaneously. 3. The temperature wave and pressure wave may travel with different speed and their direction of movement may even reverse. In the upper as well as in the lower layer, the disturbance develops (damps) when the ridge moves into the region of divergence (convergence) or the trough moves into the region of convergence (divergence). 4. The amplitude as well as the speed of movement of the disturbance varies with time. They depend not only on the structure of the basic current and the wave length but also on the vertical structure of the disturbance as well. 5. The periodically varied stable disturbances may increase or decrease in amplitude snore than 250% in one day during the stage of development. Thus the ordinarily observed large variation of circulation in westerly belt may not be a phenomenon of instability.