28 



On the Distrilmtioa of Cyclonic Precipitation in Japan. 



Moreover, even if the isotherms were originally parallel to the 

 latitude, they will be distorted counterclockwise as is well known, 

 since the artificial assumption does not hold that the earth's 

 surface as a sensitive heat reservoir keeps the air always in the 

 temperature prescribed for the latitude. These efïects taken 

 altogether, will tend to drive the area of the maximum precipita- 

 tion toward the eastern side of the depression. 



(2) Geographical thermal influences. When the coast line is 

 straight and the air is everywhere saturated, the reasonings of the 

 preceding paragraph exactly apply to this case, only that the 

 temperature gradient is here everywhere small, except in vicinity 

 of tlie coast line. The part of the precipitation due to the term 

 R of the preceding paragraph will be abundant on the warmer 

 half-plane. The influence of the term R' will be only sensible in 

 a narrow zone along the coast line if the variation of temperature 

 across the coast be abrupt or discontinuous. If in the land area 

 the air is not saturated, the case may differ, according as the 

 absolute humidity is greater or less than on the sea. In the 

 special case when in summer the absolute humidity on a very arid 

 land is small compared with that on tlie colder sea, the result will 

 1)0 reverse to that in tlie above case, so far as we take no account 



of the horizontal transport. The as- 

 cending current must, however, in 

 either case be carried leeward as al- 

 ready remarked. Hence we can expect 

 precipitation on the coast of a dry land 

 where the wind comes from the sea. 

 In the normal case, when the air is 

 everywhere saturated, the isohyets will 

 simply be twisted clockwise, so as to 

 increase the precipitation on the coast 

 lying on that side of the centre, which 

 viewed from the centre have the warm- 

 er half plane on the right side. 



(3) Hydrodynamical topographical influence. Suppose AB 

 is a portion of the coast line bordering the sea on its right 



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