Rainfall. China is impacted by cold, dry, continental air, but the warm, humid, oceanic air brings in most of its rainfall. During the summer this sea air reaches further into the continent, sometimes as far as Mongolia. Naturally, a great deal more rain falls on South China than on North China. To the south, near the sources of cloud-carrying winds, rainfall is heavy because the coast is backed by mountains and this situation gives rise to moisture as it comes in from the ocean. Rain in the South averages almost sixty inches a year, and some coastal mountains receive as much as a hundred inches. This rainfall, together with run-off from the central Asian massif, supplies South China with plenty of water, which is used not only for irrigating rice fields but also for transportation. The network of navigable streams and canals, which covers most of...