On the Eiïect of Topo^-raphy on the Procipitation in .Japan. 



15 



diagram for a given region, we classify different years according as 

 the precipitation of a certain station situated in the said region, is 

 above or below the normal value, and mark the corresponding 

 points with proper signs. Then if the station is especially sensitive 

 to the gradient, the points belonging to the two classes will be 

 separated by a definite line of demarcation on the area of the dia- 

 gram. Carrying out the procedure for the different stations chosen 

 above, it w^as found that some Pacific stations such as Numadu, 

 Hamamatu, Koti etc. show striking dependency on the topographi- 

 cal rain, whereas most of the Japan Sea stations show rather 

 irregular aspects. It was suspected that the latter fact could be 

 explained by the influence of the high pressure zone along the 

 axial line of the land. Choosing a number of stations near the 

 axial lines, we have calculated the gradient between these axial 

 stations and the coastal stations on both sides of the land res- 

 pectively. It was found that the gradient between the axial part 

 and the Pacific coast, say s, is generally parallel or at least have the 

 same sign with the a;- component above obtained, whereas the 

 pressure difference between the axial and the Japan Sea regions, say 

 n, has frequently different signs with x. On plotting n-y diagram 

 instead of x-y diagram, however, the distribution of the years 

 belonging to the above two classes for the case of tlie Japan Sea 

 stations is still very irregular. We may therefore infer that on 

 this side of Japan some other terms predominates over the effect 

 above considered, as far as the annual amount of precipitation is 

 concerned. We will resume the question in a later section in 

 connection with the seasonal distribution. 



10. A similar comparison can be made with respect to the 



Table VII. 



