The author, meteorologist at the Military Aeronautical College at Tokorozawa near Tokyo, very often observed dust storms with interest, occurring there during recent ten years. He already contributed the reports in them twice to this Journal. In the present paper he classides the dust storm into the following three classes:- The first class, Funnel, shaped or smork column type. Most frequent, average height is 50cm; diameter near the ground is about 2 to 10 metres, duration of existence, 5 minute to quater an hour; sense of revolution is sometimes right and sometimes left. The s_??_cond class, Cylind_??_cal type; rather frequent, so-called dust devil in India; several columns with diameters of a few metres appear at the same time reaching the height about 300-600m. Their colour is dark; they have sharp, well defined edges at their middle parts, while rather diffused rims at their tops and feet. Their existing duration is about 10 minutes, after dissolving of the columns dust smork is still seen above the sky for some thirty minutes. Plate 13. shows “Dust devil” and Funnel shaped one. The third class, Group type: many whirls revolve round along one and the same circular orbit; the sense of revolution is the same as that of the rotation of each whirl. The author noticed the sudden change of the sense of rotation of a whirl as Dr. E. H. Hankin(1) has formerly remarked. He observed it at the distance of about 4 metres. At first the rotation was of cyclonic sense, then suddenly it changed to anticyclonic and after about one minute the original rotation is resumed. Then the whirl seemed hesitating to rotate and all the sudden the anticyclonic rotation started again when the whirl displaced about 4 or 5 metres. After a while it vanished. The author hardly believe that he saw an ilusion. An aviator in the college once got into such a dust devil at the height of 400 meters. (March 13, 1924). All the radders of his machine fell off and he lost control of it. For a while came back again the resistance on radders and he was safe. The author once ventured to walk into the dust storm. He felt some lift with his body. He estimated the wind velocity at 30m/s. People in this vicinity sometimes were injured in the dust storm, which perhaps due to the sudden fall of pressure of some 5 or 6mm of mercury. Once a dust storm passed on across a wcoden house at a corner of the Aerodrome. Windor panes were broken and fell outside. A part of the roof of the house was torn off. The progressive motion of the dust storm seems to be controlled by thegeneral flow of air at that place. It was known that dust storm sometimes accompani_??_s electric discharge. On March 19, 1924 an air-ship filled with hydrogen, somewhat old and impure, exploded. The day was especially marked with dust storm and the author believes that the airship, being painted with metalic powder, must have the same electric potential as_??_the surrounding air. On encountering a dust storm which ascended from the ground, the inevitable fate must be the electric discharge dué to the great potential differerence between the airship and the dust columns and consequent explosion of hydrogen. Meteorological conditions when the dust storm oceurs. The occurrence of the storm is confined in February, March and April. Two or three hours after the sunrise the storm begins to be formed and it is most vigorous at the noontide, and gradually subsides at the sunset. The dust-storm never occurs when it is raining. The humidity of air during the occurrence is very low, never exceeds 40%. On that occasion the wind velocity is always small, and temperature is rather high. The dust storm preferably occurs on a day of anticyclonic weather in which morning temperature is rather low which followed by a sudden rise caused by the solar radiation.
The author reckoned the average weather elements during the sericultural season in Nagano prefecture, Japan. Comparing the results with the corresponding crops of cocoon, he explained the advantagious and disadvantagious effects of weather on the sericulture. He also calculated the correlation coefficients between the cocoon crops and the average weather elemnets during the sericultural season and obtained for years 1907-1920 the following fignres:-
The author picked up 21 case of newly born cyclones in Japan Sea from the end of 1920 to June 1923. They appear mostly in the winter months i.e. Month Oct. Nov. Dec. Jan. Feb. march April June Frequency 1 2 3 4 5 2 1 2 of these cyclones 5 classes may be distinguished with respect to their birth places. He examined the condition prevailing before or at the time of the birth of the cyclones and noticed that a characteristic sudden rises and falls of temperature were always seen. Thus he insists that the cyclones may be the products on the lines of iscontinuity, developing from the horizontal vorticity effected by the orographic conditions as S. Fujiwhara has already has already suggested. The author recommends the hourly observations in order to issue timely warning against the sudden break out of the cyclone of the kind. (S. F.)
Three photographs of lightning flashes were taken on the evening of Aug. 20, 1924 at about 7 o'clock by Mr. T. Takayama, my assistant, at the Central Meteorological Observatory, Tokyo. Two of them are shown in Pl. 1. The camera with film was left open until the moment when a lightning fiash was seen, then it was closed and the film was changed with a new one and then again the camera was open. Thus seven films were exposed, of which only three had the picture of flashes which are none of the ordinary fork or zigzag lightning, but are something of the nature of bead and rocket lightnings discharging into air. In fig. a or Pl. 12, 4 groups and in fig. b 3 groups of lightning flashes of nearly the same height are shown. In the other photograph (omitted) one group is seen very near the horizon. Each group of flashes consists of luminous spots and branching line-flashes. The following points perhaps are worth mentioning. (1.) The photographs were taken facing towards the north and the thunder clouds were then shifting to the east. The luminous spots, circular in the photographs perhaps were actually sphericel, assemble in western part of each group and those in the eastern part have line lightnings starting from them. (2) The luminous spots are mostly arranged along some curved lines (invisille), which lie mainly in east-west direction with more or less inclination. (3) There are various sizes of spots. (4) Most of the spots are circular; only 2 out of nearly 100 are elongated a little in the east-west direction (See fig. b, the central group, central part) (5) The line lightnings are not those. bridging one electric polo to the other, but they are radiating from same _??_mmon center into air. (6) They have always spot lights at their feet. The line lighnings bave pin shape, lecoming gradually slender, ending at last at shatp _??_nds. (8) The terminal parts of the line lightnings have a tendency to curve towards the east. (9) The biggest line lightning of each group extends. always toward the most approximate east and smaller ones are gradually distributed upeard and downward in the order of magnitude. (10) The line lightnings have branches. which have no spot light at their feet. (11) Some of the line lightnings have zigzag outline as if they were bracteated. (12) In the central part of each groups diffused light is seen. Many hypotheses may be formed to explain the above phenomana, but they cannot be conchusive. Only the conclusion that we can draw is that the so called bead and rccket lightnings are real. phenomena having objective existence.