Chapter 11. On criteria of stability of zonal circulation. In the present chapter we verified that the criterion of stability of zonal circulation due to Helmholtz is the same with our criterion obtained in our investigation part VI, provided that two air rings are transformed into a continuous medium Chapter 12. Horizontal stability in anticyclone. We obtained the criterion of horizontal stability in anticyclone Chapter 13. General stability in frontal zone. We obtained the criterion of general stability in frontal zone.
There are three types of distribution of convectional rainfall intensity. (a) a peak type. (b) several peaks type, and (c) mountain-range type. These typ_??_s are typically shown in Fig. 1. T (=mean period of each intensity curves in min), Tm (=the period of the maximum intensity), I (=mean intensity in millimeter per 10min.), Im (=the maximum intensity in millimeter per 10min.), Tm/T, Im/I etc. are shown in Table 1.It is clear from this table that the amount of rainfall of a peak type rain is the greatest. The relations between T and Tm, and between I and Im of each type are shown in Fig. 2 and 3. The period of the maximum intensity increases linearly proportionally with the mean period of each rainfall intensity, but the maximum intensity rapidly increases. The variation of rainfall intensity with the mean period is shown in Fig. 4. The most observed points are enclosed in the closed curve. That is the range, in which the intensity and period are frequently observed, are limited in 24min. <T<47min., and 0.6mm/10min. <I<5.1mm/10min. Similarly 17min. <Tm<70min., and 1.4mm/10min. <Im<10.3mm/10min. The value of the maximum intensity and its period for convectional rain increase proportionally amount of rainfall. Next, the variation of rainfall intensity, air temperature (t) and rain temperature (T) for some rainfall are shown in Fig. 8 and it seems that the maximum number of rain droped per unit area (mark M) occurs a few minutes before the maximum intensity. In Fig. 9 the model of rainfall is shown.
In this paper the author observed rain-water temperature for a year, and discussed some properties of rain-water temperature. The number of times which observed rain temperature is 218, and observed rain is 56 times. There are many kinds of rainfall types, but these kinds will be classified into four great divisions as following, i) convectional type, ii) anti-cyclonic type, iii) cyclonic type, and iv) middle type. In Fig. 2 the relation between τ (=t-T. t: air temperature and T: rain-water temperature) and t is shown, and frequency of τ for each types of rainfall is tabulated in percentage for total. It follows from these figures and table that the range of rain-water temperature increases proportionally to the air-temperature, and there was not an inversion of temperature when the rainfall types is convectional. But at cyclonic type rainfall the inversion of temperature was observed, and the rainfall will begin at this layer. As shown in Fig. 4 the relation between fall of air temperature and fall of rain-water temperature, and between the former and the maximum τ are almost linear, while the variation of fall of τ with fall of air temperature is not systematical. The variation of fall of air temperature with rain duration is shown in Fig. 5 and the variation of fall of rain-water temperature is shown in Fig. 6. It appears from these figures that the maximum of fall of air and rain-water temperature occurs at five or six hours of rain duration. The relation between fall and the maximum of τ of convectional rain and rain duration is shown in Fig. 7. The maximum value of τ is almost constant, and independent of rain duration. The most active centre of convectional rain appears after six or seven hours from benining of the rain. It will be said from these facts that the convectional rain begins from the bottom or upper part of cumulo-nimbus, and the former rain phenomena gradually extends to the upper part of the clouds, and the later rain to the bottom part. Next, the relations between amount of rainfall and fall of air and rain-water temperature of convectional rain are shown in Fig. 8, and the maximum τ and fall of τ are shown in Fig. 9.
The present writers have plotted dry and pseudo-wet-bulb temperatures for the individual Batavia flights(1). In table I we give a brief resumé of 57 soundings used in this paper. It conforms well with the usual expectations of equatorial maritime air, being quite wet and unstable. The stability and mean va ue of greatest realizable energy up to 300mm Hg level for rainy and dry season are as follows:
The results of the supplementary survey in the field are described in this paper as the continuation of the former report. The chief object of this work is to determine the vertical distribution of the water content of soil in the frozen zone as well as in the layers under the freeing line. The results are shown in the Figures. As a rule the frozen layer contains excessive water than the soil saturated with water, and a dry layer is always found just below the freezing line, the soil further below being less descicated. The water content was measured for many samples of frozen soil which show various modes of segregation of ice. The photographs of samples and the amounts of water content were tabulated.