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On the Edge of the North China Plain
The city has shifted location several times in the past
several thousand years, but the spatial dimensions have remained
fairly constant over time. The present city center is 39o56' N,
116o20' E, at an elevation of 44.38 meters above sea level, the
northwestern corner rising mere 10 meters above the southeast.
Originally the city stood on a slight ridge of land formed by alluvial
deposits. This silted base, the edge of the North China Plain, was
built up over time by the sand carried downstream through the
mountains by the Yongding River in the west and the Chaobai River in
the east. In terms of outlying geographical features,
the extensive Yanshan Mountain range forms a silvan screen to the
northeast, the long, winding Taihang Mountain range to the west. Just
beyond, to the northwest, the vast Mongolian plateau begins. The Gulf
of Bohai lies 113 kilometers to the east and to the south, the vast
North China Plain. Geologists call this small gulf-shaped plain
surrounding Beijing the “Beijing Gulf” though in fact, the city sits
off in its southwestern corner, Early writers described the setting
with the sea on one side and the mountains in the background as a
“heavenly paradise,” a “city of the gods.” Beijing has a
continental monsoon climate commonly found in the temperate zone. In
winter, cold, dry winds blow out of Siberia and Mongolia in the
northwest; in summer, warm, moist air currents from the southeast take
over. A general change of wind direction occurs in March or April and
again in September. Wind velocity in Beijing is comparatively low,
averaging 2 meter/second. The average annual rainfall of 630
millimeters is regarded as a generous “heavenly endowment” for North
China, which is otherwise predominantly dry and short of rain.
The coldest month in Beijing is January, with an average temperature
of – 4.7oC. The hottest month is July, with an average of 26.1oC.
Rapid temperature increases in the spring are often accompanied by
sandstorms, but windless days in that season are wonderfully pleasant.
Autumn, though short-lived, is a concentrated stretch of clear, crisp
days and patchwork trees. Historically speaking, the
mountains to the north, east and west acted as boundaries with
outlying pasture lands. Communities in the present–day “Beijing Gulf”
traded with the nomadic tribes who lived out beyond Gubeikou in the
north and Nankou in the west and maintained frequent commercial
contact with people of the central plain region settled along the
Yellow River. It was trade and the pivotal role of the area as a
center of commerce which gave rise to the ancient city of Ji. |
