For weather forecasting in Japan where warm and cold currents are complicated in the neighbouring seas, wide attention must be always payed to their balance. For this purpose water temperatures are informed every day from ships at sea to the Central Meteorological Observatory, and are put on weather charts as well as ordinary meteorological data. In the present paper it is pointed out that daily pressure distributions in the neighbourhood of Japan are controlled to some extent by the predominance of the Kurile and other cold currents. For example, as for the difference of mean pressures over the Yellow Sea and over North China, the amount of its increase or decrease after six or twelve hours can be well estimated from the area of the cold current occupying the Sea.
In Kwanto district, when the wind is northeasterly, rain is often experienced even though there is neither low nor front in the synoptic chart. Such rain was researched and it was found that a low or front, especially a warm front existed in the upper layers, say at 1000m. And the rain was explained to be caused by a convergence due to a low or front in the upper layers.
Blackett(1) has suggested that the “temperature effect” of cosmic rays is due to the vertical shift of the layer in which mesotrons are formed, and he has further suggested that it may be possible to correlate cosmic-ray data with the structure of depressions. Loughridge and Gast(2) have pointed out that cosmic-ray data in America indicate a noticeable change in intensity at the fronts which separate different air-masses. The polar continental (Pc) air-mass(3) originates in Manchuria and Siberia and comes to Japan proper as the northwest monsoon in the colder half of the year. The tropical maritime (Tm) air-mass flowing from the North Pacific subtropical high pressure belt comes to Japan proper as the southerly tropical air mainly in the warmer half of the year. The polar maritime (Pm) air-mass originates in the Okhotsk Sea and sea to the east of Japan and comes to Japan proper as the mild northeast wind in the rainy season. The Pm air-mass found in Japan is shallow, but plays an important weather rôle. The Pm air-mass is seldom thicker than 2000 m and is usually overrun by a Tm air-mass; the interaction of these two air-masses results in forming a stationary front and is responsible for the gloomy, rainy weather during the Bai-u period of Japan. There are two other modified polar continental air-masses, which lose their original coldness and dryness in the lower layers. One comes to Japan proper by the sea route from the northwest, and the air-mass type is transformed from the fresh one into the modified one (NPc 1). The other arrives in North and Central China by the land route and then comes to us by the sea route, with the general westerly wind (NPc 2). These air-masses were identified, using the synoptic charts analysed by the Forecasting Division of the Central Meteorological Observatory, Tõkyõ. Cosmic-ray intensities measured with a Steinke cosmic-ray meter and their barometer effects under various air-ma s conditions prevailing in Tokyo during the year 1937 are shown in the annexed table. We find thus: (1) both the correlation coefficient and the barometric coefficient are relatively high in the fresh Pc air-mass and Tm air-mass, and show a gradual decrease as the air-mass type is transformed from the fresh one into the modified one; (2) the correlation coefficient and the barometric coefficient are very low in a Pm air-mass which is shallow and is overrun by a Tm air-mass; (3) the reduced cosmic-ray intensity is relatively low in warm air (Tm and Pm), but is high in cold air (Pc).
In the preceding paper, we have pointed out that cosmic-ray data in Japan indicate a noticeable change in intensity under different air-mass conditions. It is shown below in detail that the cosmic-ray intensity measured during the year 1937 with a Steinke cosmic-ray meter inside 10cm of lead is higher on southeast side of a cyclone and lower on west side of it, which results from the instability of mesotrons. In Fig. 1 the cyclonic structure after the Norwegian school is shown. In this diagram the light solid lines represent isobars. The right-hand discontinuity of the cyclone stands for a warm front, for here the warm tropical air is forced to override a wedge of cold air underlying it. The left-hand portion of the cyclone stands for the cold front of the system-a wedge of cold air which is displacing the warm air. In normal cases the field of flow is such that the cold front travels faster so that it soon begins to overtake the warm front. The system thus composed is called an occluded front. In Japan proper the air behind a cold front is generally colder than that ahead of a warm front, having had a shorter trajectory over relatively warm sea areas. From cosmic-ray observations the writers considered it worth the trouble to compile a diagram (Fig. 2) which shows cosmic-ray intensity in the cyclonic area. The method used was as follows: In each case of 11 developed depressions during the year 1937 where a depression existed and its center was determinable within the radius of about 1100km (or 10 degrees of latitude) from Tokyo, all the hourly cosmic-ray intensities (number of observations=359) and barometric readings were plotted on a large composite diagram. For simplification the cosmic-ray intensities were then reduced to the normal standard pressure, using the absorption coefficient (μ=9.52×10-3/cm Hg). Numbers of the cosmic-ray data were then reduced, by collecting the adjacent ones, to 49 groups and each group was replaced by one value indicating the average intensity. These average values are the ones actually shown on the diagram. A statistic representation of the data for the year 1937 is shown in Fig. 2. Observations reported in the preceding paper (Cosmic-Ray Intensities and AirMasses) tend to confirm the above results, and the view now generally held is that positive changes of cosmic rays are associated with the passage of airmasses of polar origin and negative changes with that of air-masses of tropical origin. Besides the very striking effect in reduced cosmic-ray intensities associated with the passage of typical cyclones (having low values in the warm-front face and high values in the cold rear), we should emphasize the marked effect of the presence and currents of different sorts of air-masses in the high troposphere, the air-masses being named according to their origin. The following outlines give the general rela-tions of the cosmic-ray intensity with the passage of different fronts. The cold front and the warm front generally give changes of 2 percent. These are, of course, average conditions which are frequently observed over Japan proper. Individual cases may show quite different characteristics. A similar determination of the influence of migratory antieyclones on cosmic-ray intensities was carried out. In Fig. 3, it is generally seen that the cosmic-ray intensity is highest in the front of anticyclones and lowest in the rear. Positive changes in cosmic-ray intensities are associated with the passage of cold air-masses of polar origin in the front of anticyclones and negative changes with that of warm air-masses of tropical origin in the rear. The actual intensity of cosmic rays in the different quadrants of an anticyclone is given in the following table, based on 643 hourly obser_??_ations of 25 typical anticyclones.
G. I. Taylor introduced two kinds of correlation functions to describe the nature of micro-turbulence in turbulent flow. Mean radius and mean life of micro-turbulence in the atmosphere were determined after consideration of such correlation functions and the following relations were found. where η is eddy kinematic viscosity, τ0 mean life and u' fluctuation of the velocity. where λ is mean radius of the micro-turbulence, molecular kinematic viscosity. Numerical values of mean life and mean radius of the micro-trubulence in the atmosphere were calculated from observations and it was found that they are about 6cm. and 50 sec. respectively.
A set of charts representing the horizontal distribution of equivalent potential temperatures in Kyusyu during the period from 20th of June to 10th of September, 1939, was made. The authors then investigated the relations between the occurrence of heat thunderstorms and the surface distribution of equivalent potential temperatures, expecting that high equivalent potential temperatures are responsible for thundery conditions. Unexpectedly, however, heat thunderstorms did not necessarily originate over the regions where the equivalent potential temperatures were high. The adopted method of determining the thundery conditions was to get the critical values of equipotential temperature at which a thunderstorm has not cccurred, though these values varied at each station. After statistical studies, more than 80% of all the thunderstorms occurred when the equivalent potential temperatures at stations near the origin were higher than the critical values.
The coefficients of correlation between the yield of upland rice-crops and the weather factors (monthly mean temperature, monthly amount of rainfall and monthly total hours of sunshine) have been calculated by the method previously reported in this magazine, for each prefecture in Japan, each from April to October. The correlation coefficients calculated are shown in tables 1, 2, 3, and they indicate that rainfall has most important influence on the yield of upland rice-crop in every prefecture, for the upland rice plant is susceptible to drought injuries. It is noteworthy in this investigation that the coefficients of correlation between the yield and rainfall at the ear-appearing period are almost positive even in the northern parts of Japan, where summer temperature has large influence upon the yield as a limiting factor. In a word, from the correlation coefficient calculated we see that rainy weather without wet or cold injuries is favourable for the upland ricecrop.