中国本部与美国之东部均各位於北温带大陆之东岸,惟中国之最南端较之美国南部纬度低十度而已,此就地理情形而言也。就气候情况言之,则二者颇相类似。若以其同纬度各地相比较则均有酷热之夏季及严寒之冬季。此大陆性之显著,乃其相似者一也。

The rainfall of China is scanty when compared with the northeas ern partof the United States of Ameriea, almost identical in location and in latitude,The aridity of north China was found to be due to the following four causes.