This is the final report o n our analysis during winter months. The model of the large-scale atmospheric disturbance which was suggested in former reports is made more complete through wind field analysis. It becomes clear that there is a rather close relation between the trough and the divergence field, and that the middle layer divergence in front of the trough is not only an important factor on the cyclone development, but also acts as frontogenesis resulting in the so-called polar front. The vertical motion caused by divergence field explains the characteristic temperature field accompanied by a trough. This seems also to be applicable to the disturbance of a larger scale, such as revealed by 5-day mean.
From the results of str e amline analyses of typhoons, it is found that the point which corresponds to Scherhag's “delta”appears in the moving direction of typhoon, and approaches to the typhoon center with height. And the fact that the direction from the typhoon center to this delta point agrees with the direction of a steering current and typhoon moves along this direction, is clarified.
In the present paper, the motion of tropical cyclones in a circular or hyperbolic flow of uniform vorticity is treated. The motion in a linear flow is also dealt with for the sake of comparison with the other results of the author and others. The quantitative formulation of the steering principle is attempted. The motion will trace a trochoid in a linear flow, an epicyclic in a circular flow and a similar motion to the former two in a hyperbolic flow. The amplitude an d period of oscillation depend on the wind speed of the basic current and on the size and intensity of the storm and not on the Coriolis parameter. Both the speed and direction of a tropical cyclone is considerably affected by its oscillating motion. Also, the storm will sometimes describe a loop path as a result of the oscillation.
It is shown that the hyd r o dynamical model of the vorticity waves proposed by RossBY can be safely applied to the easterly waves in the tropical latitudes. A simple explanation for the kinematics of the meandering and the well developed blocks of the westerlies in the middle latitudes as well as an account for the quasi-horizontal eddy motion and the equatorial westerlies frequently observed in the equatorial area is proposed, using the known solution of the nonlinear vorticity equation.
With the numerical calculation of the theoretical formula of primary and secondary scattering obtained in the second paper of this series with varying coefficient of extinction, the effect of the optical thickness of the atmosphere on the distribution in the sun's vertical plane was discussed when the sun's elevation angle was 60° and 30°. The result of calculation shows that the contribution of seco nciary scattering increases with an increasing value of scattering coefficient. Taking the intensity at the zenith as a unit the relative intensities at various zenith angles were compared and were com pared with the observed values of C. DORNO and F. LINDHOLM or O. ECKEL which were obtained at positions of various elevation above sea level. The theory shows that the relativeinten sities at, a comparatively large zenith angle especially at 60° always increases with decreasing optical thickness of the atmo s phere and this was confirmed by the observed results qualitatively at both of the two elevation angles of the sun. The anomalous large value of the relative intensity at the zenith angle of 60°observed by C. DORNO and F. LINDHOLM at the sun's elevation of 30° at Muottas Muraigl (2450 m) and also that observed by O. ECKEL at Gmunden (430 m) at the sun's elevation of 60° when Föhn-weather prevailed were pointed out. As a possible cause of this anomaly the influence of ozone absorption which spreads downward and then decreases the scattering layer was suggested.
To measure velocities of currents automatically, the author has made a recording current meter using a phototube, in which the intermittent, photoelectric current is depicted on a chart of a recorder on deck. The speed and direction of water current can be measured respectively by the time intervals and by the intensity of photoelectric current; Experiments on the sea have shown that by using the current meter, the actual under-water conditions can be immediately observed, and fine, accurate and rapid observations of water current have been made possible.
Microphotographs of Ice Crystal in the Air (abbreviated as ICA for shortness in the text) are taken. From the measurement of their prints the size of ICAs, their space density and their properties are studied. Also the axis ratios of hexagonal twin prisms are measured, auxiliary axis 2a=53μ principal axis 2c=83μ, and c/a =1.6 being the results. For hexagonal plate crystals 2a=100μ, c= 31μ. The Mean mass of hexagonal twin prism is 0.141 x 10-6 gr., and that of hexagonal plate crystal 0.135 x 10-6 gr. Among ICAs which come down at the same time and place, there exists a peculiar propensity of taking almost the same shape. The adhesion phenomenon of one crystal to another is frequently observed at the place where a solid angle is formed.
To the fog which was produced at the time of adiabatic expansion in the expansion chamber, we applied a near infra-red ray with the wave lengths of 1,307μ, and 1.216μ which have no connection with the absorption band of water vapour. From the ratio of the light transmission for each wave length we estimated the sizes of fog particles. From this we examined the effect of nuclization and the effect by the ultra-violet ray which modified the aforesaid effect of nuclization of AgI, NaC1 and the confined air in the room.
By applying the wave-me c hanical treatments in atomic collisions the author investigates the scattering of the plane electromagnetic waves by a continuous inhomogeneity with spherical symmetry in a homogeneous medium. An example case is given for such a spatial distribution of an inhomogeneity in a medium as exp(-R2/R02).