On Orographic Effect on the Cyclonic Rainfall

[摘要] D. Nisimura found the conspicuous orographic effect on the distribution of the amount of rainfall due to cyclones in Japan. Since his result is very important for the practical weatherforcasting, we have studied after the suggestion of Prof. S. Fujiwhara, the same problem with the recent data in the district around Hirosima which is one of the anomalous districts, pointed out by Nisimura and extended it into surrounding districts, Tyûgoku and Sikoku. We have studied all cases up to the end of 1932 of rainfalls more than 50mm. that lasted over one or several days due to cyclones. The same general results as Nisimura's were obtained with some supplement. The most remarkable conclusion is as follows; the cyclones passing from west to east over the Japan Sea or the Inland Sea of Japan and lines of discontinuity trending east to west over the neighbourhood of Hirosima caused anomalously heavy rainfalls in this district. But we have never experienced any similar phenomena of cyclones passing over the Pacific Ocean nor in a case of typhoon passing the Japan Sea.

[学科分类] 大气科学