Monsoon winds, caused by differences in the heat-absorbing
capacity of the continent and the ocean, dominate the climate.
Alternating seasonal air-mass movements and accompanying winds are
moist in summer and dry in winter. The advance and retreat of the
monsoons account in large degree for the timing of the rainy season
and the amount of rainfall throughout the country. Tremendous
differences in latitude, longitude, and altitude give rise to sharp
variations in precipitation and temperature within China. Although
most of the country lies in the temperate belt, its climatic
patterns are complex.
China's northernmost point lies along the Heilong Jiang in
Heilongjiang Province in the cold-temperate zone; its southernmost
point, Hainan Island, has a tropical climate (see
table 4, Appendix A). Temperature differences in winter are great, but in summer the
diversity is considerably less. For example, the northern portions
of Heilongjiang Province experience an average January mean
temperature of below 0°C, and the reading may drop to minus
the average July mean in the same area may exceed 20°C. By
contrast, the central and southern parts of Guangdong Province
experience an average January temperature of above 10°C, while
July mean is about 28°C.
Precipitation varies regionally even more than temperature.
China south of the Qin Ling experiences abundant rainfall, most of
it coming with the summer monsoons. To the north and west of the
range, however, rainfall is uncertain. The farther north and west
one moves, the scantier and more uncertain it becomes. The
northwest has the lowest annual rainfall in the country and no
precipitation at all in its desert areas.
Data as of July 1987