The annual migration of the equatorial belt of high temperature causes the wind system to migrate. The velocities of the prevailing westerly winds are much greater in winter than in summer. Places in the equatorial belt will experience mild easterly upper air currents during the summer. When the doldrums are farthest north, the trade wind from the southern hemisphere crosses the equator. When the doldrums are farthest south, the trade wind from the northern hemisphere crosses the equator.
In Japan, recently, there appeared several papers on the theory of the general circulation of the earth's atmosphere by the Various authors as Y. Kodaira, K. Terada and H. Arakawa. Their theories are essentially either modified or generalized ones of the classical theory by A. Oberbeck. In general, almost all the authors seem to accept the acceleration due to gravity as the difference of that of the centrifugal force due to the earth's rotation from the astronomical attraction and are used to treat it as independent of latitude in the equation of motion. Such a procedure will of course be valid, if the problem under consideration be confined to that of a local phenomenon on the earth and at the same time the air be incompressible, yet there remains some suspicion in such an idea when we treat the motion in a large scale such as the general circulation and the air is compressible subject to, say, the thermal expansion as assumed by A. Oberbeck and others. The result of our calculation, including the effect of the centrifugal force, shows that the equatorial belt of high pressure derived from the theory of A. Oberbeck is shifted polewards a little way, though the exact computation is difficult. The mode of motion along parallel longitudes will be discussed in the second report.