Abstract
In my previous paper, I have discussed the effect of topography on the wave-length and the amplitude of Helmholtz Wave for a semi-circular cylindrical mountain range and some other cases, neglecting the effect of earth's boundary formally and here I studied on the influence of earth's boundary on Helmholtz wave. Then the next conclusion was drawn. If the temperatures of the upper and lower mediums, and the differences of the velocities, the temperatures between the upper medium and the lower medium are all constants, the stable wave-length near the earth's surface must be considerable longer and the amplitude smaller than those at a surface of discontinuity very high above the earth's surface, and the effect is more remarkable for long wave than for short wave. In other words, the appearance of short wave is almost independent of the effect of the boundary but that of long wave is more frequent in upper atmosphere than lower one, in which short wave has a tendency to prevail by the effect of the earth's surface. Such a tendency can be verified by the results of observation of wave cloud done by Mr. S. Ishimaru, and the amplitude of short wave has nearly nothing to do with the effect of the boundary except very near the earth, but that of lo_??_g wave in upper region is greater than that of in lower region under the influence of the earth's surface.
