The primary purpose of this paper is to give the statistical discussion on the relation between the elements observed by means of pilot balloons and the coming weather in such a way as to provide means for forecasting weather. To this end the data are presented in a series of tables containing information in considerable detail.
(a)
Turnng of winds with altitude from the surface direction and the coming weather.In Tables 1 and 2 are given, respectively, the frequency of clockwise and counterclockwise turning and the frequency of each turning bringing rain during the period of 24 hours after the time of observation in its train. In Tôkyô, clockwise turning is more frequent than counterclockwise, and there is a remarkable tendency that the percentage of coming rain during the period of 24 hours after the time of observation of clockwise turning is larger than that of counterclockwise turning. This law was formerly pointed out by Prof. F. M. Exner and ascertained by Dr. R. Sekiguti and Dr. Y. Horiguti, using only 10 observations at Kôbe, Japan; but in this paper more than 2000, observations were used.
(b)
Direction of wind at the level of 3000 meters and the coming weather.In Table 3 and 4, are given the frequency of upper air current from different directions and the frequency of current bringing rain during the period of 24 hours after the time of observation in its train. In Japan, the direction of upper air current is always from the west except short period in summer. But the author proved statistically, if the direction of free-air winds is E-ly, then it indicate, with no exception, fair weather during the following period of 24 hours at least.
There is a remarkable tendency that, according to the direction of free-air winds at 3000 meters is whether with west to north-northwest or with west-southwest to south, the coming weather can be foreknown with sufficient accuracy for the “fair-weather method” which is the weakness of the observation of pilot-balloons as a means of upper-air exploration. The second law, formerlly reported by Prof. S. Fujiwhara, serves as a reliable guide for forecasting the weather of Tôkyô (35°41'N) Oosaka (34°39'N) and Hukuoka (33°35'N) and is not useful for forecasting the weather of Naha (26°12'N); hence it seems the second law is the sequence of the general circulation of the atmosphere as a whole.
(c)
Velocity of free-air wind at the level of 3000 meters and the coming weather.In Table 5 and 6 are given, the frequency of different velocities and the frequenency of winds bringing rain during the period of 24 hours after the time of observeation in its train. In Tôkyô, it seems the coming weather is fair if the uppper-air current speed is large enough. For the observations of hurricane, this law was, with no exception, ascertained. For the observations of Oosaka, Hukuoka and Naha, the data was too wanting to check this law.
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