颱風と上層氣流觀測の一例

Abstract

In August of 1924 a typhoon visited Ryukyu Islands. It strolled about the vicinity for about a week describing a very singular path having two loops. This typhoon was already reported by the Central Meteorological Obserbatry Tokyo. (1)Mr. Y. Horiguti precisely investigated this typhoon. (2) The author, having the intention to observe the cloud movement in typhoons with his new nephoscope, (3) had proceeded to Naha, the central city of the Islands during the vacation, and had an excellent opportunity for his purpose. The results of his observation are shown in Figures, 1 to 5 in Japanese pp. 221-226. The principal results are as follows:(1) The motion of clouds in every level was regular within 500km. radius from the typhoon center, angle of deviation with the isobors increasing as the height increases.(2) In every height the angle of deviation had a tendency to decrease as approaching to the center of typhoon.(3) The angles of deviation of the surface winds were less than 75°, their mean being about 50°.(4) The angle of deviation of the direction of lower clouds from the surface gradient was about 85° and it tended to 90° (gradient wind) as the center was approached.(5) It is probable that the gradient wind direction was attained at the top most layer of the lower cloud.(6) The angle of deviation of the direction of middle clouds from the surface gradient was about 110° in the average and that of the upper clouds was about 130°.(7) There was outflow of upper clouds from the typhoon region at the distance of 500km and 1000km from the center with the clockwise sense of rotation facing to the earth. As is seen on fig 4. upper cloud direction changed from east to west then again to east accompanying with the change of direction of typhoon motion.