抄録
An increasing annual rainfall in Japan is statistically discussed. This variation in rainfall was paralleled with hydroelectric potential output data and flood damages in Japan, in the long run. Finally, a relationship between the rainfall and the eleven-year sunspot cycle is tested, although it is concluded the eleven-year sunspot cycle is of little importance. A hypothesis of an inerease trend of water vapour in the atmosphere for a possible cause of the generally warm and rainy years on the world-wide scale is suggested.
