The annual change of the number of fires, conflagrations and forest fires was calculated for every prefectures in Japan and compared with meteorological conditions in respective places. Changes in ten representative places, which are climatologically specialized, are graphically shown in the text. Nextly the distribution of the degree of danger in every month of the year was investigated for conflagrations and forest fires. The distribution for the period from January to June are also shown graphically in the text.
Lines of discontinuity in the atmosphere are classified into 4 types, that is, passive front, warm front, cold front and active front. If the motions of warm air mass and cold air mass are passive, such the front is called passive front. If warm air, mass moves rapidly, the front is called warm front, if cold air mass moves rapidly, cold front, and if both warm and cold air masses move rapidly, active front. And the character of these fronts are researched.
(1) Similar character of weather change is maintained during one or two months. For example, in Tokyo, if rainfalls are frequent during the former 10 days of January, they are also frequent during the following 20 days. (2) The most frequent distances between two cyclones range from 1700km to 3500km. (3) The periodicity of pressure has following character. a) 4 days periodicity is stable. b) The pressure wave which has long period and large amplitude becomes short gradually in period and amplitude. c) The same mode of the periodicity continues during 10 to 15 days. (4) Long range forecast is possible based on the nature of the periodicity above mentioned.
We classified the types of fog as dry, wet and middle one, according to the wetness of fog. We studied the mutual relation between these types, drop size and wind velocity. The results are as follow: (1) The drops are larger in wet fog than in dry one, and the critial radius between these types seems to be 10_??_12μ. (Fig. 1) (2) Wind velocity has some effects on these types; the product of the square of wind velocity, v and the radius of drops _??_ (=vza) seems to be principal factor deciding the type of fog. (Fig. 2)
There is some reason that the visbility of a terrestrial object at any direction can never be independent of the position of the sun in the sky, because the degree of the molecular scattering in the sight line is different for each position of the sun. Moreover, this scattering is some function of wave length, and also the reflective power of the earth's surface and the penetrative power of the atmosphere is the function of the wave length, therefore it is supposed that the visibility of the distant ob_??_ect depends not only on the position of the sun, but also on the spectral distribution of the light which reaches the observer's eye. To examine the primitive relations which must exist between these elements, some observations were made during the summer month of the last year. For the sake of avoiding the complexity which may arise from the other causes above mentioned, and also to make the conditions of the visibility marks the same as possible, the topography of the observing station was carefully reconnoitreed, and Mt. -Haruna, a high plateau of about 1200m above the sea level, where the air is almost clear and the various dusts are very scantly, was selected as the most suitable station for this observation. Two kinds of visibility marks were used. One of them is a set of flags, each of which consisted with rcd, white and black colour of about 50cm, Three sets of such flags were made, and each of which was installed at three directions east, south and west at about 400m from the observer. At the background of these flags, the green grass of the same tint had been grewn. As the conditions for northern direction, especially with respect to the background, are somewhat different from those of other directions, so that the observation for this direction was not executed from the beginning. As the second kind of marks, the natural mountain peaks, which were properly distributed around the observer, were used. The observations were made with the Wigand's visibility meter with the glass colour filter of several kinds. From the plentiful materials of observation, which were made each 30 minutes from 8 o'clock to 16 o'clock during one month, it was remarkably perceived that the visibility for the eastern marks, flags or mountain peaks, is better in A. N than that of A. M, and for the western marks, in the contary, the visibility is better in A. M than that of A. N. It secms, as if the visibility is better when the sun situates as the back of the observer. This variation of visibility of more remarkable when the colour filters were used, especially the red filter was most effective. Even when the flags can not be perceived by the dense fog covering the field, it was clearly perceived by using the colour filter. For the southern marks, it is expected that the variation of visibility with time becomes symmetry with respect to the true noon. It reality, the results of our observations meet this expectation. But, opposite to the above general rule that the visibility is smaller in the direction facing the sun, it is the largest at true noon. The reason of which can not be easily explained, and perhaps it may be attributed to the fact that the sun's altitude at its upper culmination exceeds more than 70° for the latitude and season of our observation, so that such cases can be considered as the same as the case when the sun is behind us.
For the sake of the members obeying the meteorological service at local stations or the isolated islands who have nol astronomcal tables, an easy method of giving the direction of the true north within the accuracy of one minute of arc, without almost any computations, was explained. If the direction of the polaris at any hour angle was observed with theodolite or likewise inst uments, the correction which must be added to this reading in order to reduce it to the true north has been given in the table on page 357. The table gives correction for tbe region between the latitude 20°N and 70°N, the sign (+) and (-) indicate that the polaris is west or east from the true north at the time of observation. As the table are given with the interval of 10° in latitude, the value at the observer's latitude must be obtained by interpoltion. In the next place, two concentric circular plate disks with an index arm should be made as Fig. 5. At the edge of the outer disk, the hour angle is graduatel, and at the perimeter of the inner disk, the corresponding azimuths are graduated. When the polaris is west from the true north, the shorter index indicates somewhere the left hand half in the inner disk, the absolute value of which is given by that graduation. The hour angle t of the polaris at the time of observation T (Japanese standard time is always ustd) can be computed by t=(T-T0)+(λ-λ0) where T0 is the time at when the polaris passes the southern meridian, in Tokyo T is the time of observation, λ0 an dλ are east longitude of Tokyo (9n18m58._??_7_??_9n19m) and the oberving station respectively. The value of T0 at the beginning of the year is known from Fig. 5. At the beginning of any date in the year it is faster 3n56m n from the value at the year's beginning, wheren is the number of days elapsed since the beginning of that year.
The result of investigation on the wa_??_er temperature of each layer of Lake Nisi is as follows: 1) The surface temperature has the maximum value 24.1°C in July, the min. value 4.4°C in Jan. an_??_ the annual range is 19.7°C, while in 70m depth the temperature has max. value 5.3°C in Dec., min. value 4.2°C in Feb. and the anuua_??_ range is 1.1°C. 2) The heat transfer is, in the surface layer, large in case of temperature increase and small in case o_??_ temperature decrease, while in d_??_ep layer the conditions are reversed. 3) The layer of jump is most conspicuops in 11-13m depth in September and its gradient of temperature is 0.99°C/m. 4) The normal deviation of deep layer temperature in Summer season shows the good correlation with the meteorological conditions of the last Winter.