Using the barotropic equation of height tendency which has been utilized in the “numerical prediction”, a formula for the displacement of extreme point was obtained. By this formula, it is shown that we may be able to predict the displacement of typhoons objectively.
Using the shadow photograph method reported in a previous paper3), size distribution of various kinds of snow crystals and snow flakes were measured. Observations were carried out at spots half way up Mt. Taisetsu and Mt. Tokachi, both 1050m above sea level, in winter of 1953-54. Fig. 1 shows size distribution for various types of single snow crystals, which were obtained within a comparatively short time of snow fall. These results were compared with those of Nakaya and Sekido, observed during the whole winter season of 1933-35. Table 1 shows that there is good coincidence among them in respect of the most probable size and range of size for crystal forms of column, simple plate and powder snow. But size and size-range differ for needle and plane dendritic crystal forms. The axis ratios of columnar crystals with the skeleton-shaped form were measured. As shown in Table 3, the average length of principal axis is 0.84mm, and the mean axis ratio is 2.48. Combining this result to those measured from the microphotographs, obtained by Nakaya and others, it is found that the value of axis ratio increases in proportion to the length of principal axis, as shown in Fig. 2. By taking photographs of snow flakes after separating into single crystals, the size distribution of snow-flake-forming crystals was measured. Table 4 represents the data obtained from the records of such snow flakes. Snow flake consisting of two crystals was investigated quantitatively. From the results, the author proposed to classify them into the following two types. One is the type in which resemblance to each other in form and size is observed for two crystals forming a snow flake. The other type is otherwise. Concerning the former, the probability of coagulation is calculated from the data of observation. It seems that its inclination is similiar to the coagulation of colloid particles of various sizes.
Some statistical properties of the hight disturbance of 500-mb surface at latitude circles of 20°, 30°, 40°, 50° and 60°N for the period of 11_??_20, Jan. 1949 are studied, expanding the height profile into Fourier series of 36 terms. Firstly, the daily spectral distribution of the square of the amplitude of each component wave (the spectrum of pressure) is obtained and the results are compared with “-7/3 power law” of the isotropic theory of turbulence. Secondly, the specific deviation of the daily spectrum which is the ratio of the standard deviation of the amplitude of each component to the time-mean value of it, is discussed in order to examine the criterion given by the stability theory of the baroclinic atmosphere. It is thought to be one of the outstanding features that the specific deviation is almost constant with the wave number. Thirdly, the meridional mass advection across the latitude circle is examined. There is a high negative correlation between the change in the zonal mean height deviation at 50°N and that at 30°N. Lastly, the technical problem of Fourier expansion, i.e. the estimation of numbers of terms which are necessary and enough for the expansion in the range of the accuracy of the observation and map analysis is presented.
In this paper the simple mathematical illustration presented by the writer in a recent paper is extended to include the correlation tensor of turbulent velocities and it is shown theoretically how the time correlation tensor of velocities observed at a fixed point is related with the space correlation tensor. The results thus derived are successfully applied to the diffusion of matters emitted from a fixed point source in a turbulent flow.