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News Analysis: Monsoons, vortexes cause extreme rains in N. China

English.news.cn   2012-08-02 18:42:56            

BEIJING, Aug. 2 (Xinhua) -- After over a week of rainy, overcast and sometimes extreme weather in Beijing, including the city's worst rainstorm in 61 years resulting in more than 70 deaths, the sky is blue on Thursday. But meteorologists say rain may fall in the capital again over next few days.

Temperatures in Beijing may drop to between 23 and 29 degrees Celsius in coming days, according to the China Meteorological Administration (CMA) on Thursday.

This summer, China's traditionally arid northern regions have received frequent downpours, causing floods, landslides and other natural disasters.

Take the capital for example, the total precipitation here has reached 368.6 mm since the start of the flood season, up 63 percent year on year to a 14-year high, said Chen Zhenlin, an official with the CMA.

He said the precipitation in central parts of north China was up 42 percent year on year, northwestern parts up 25.9 percent and northeastern parts up 18.4 percent. Precipitation in some areas have hit historical highs, he added.

June to July is the rainy season in north China, but this year's rain was exceptionally heavy. It was a result of monsoons and cold vortexes, combined with global warming, said Sun Chenghu, an expert from the National Climate Center.

The summer monsoons in East Asia were strong this year. They brought much water vapor to north China and increased rains. Also, as cold vortexes in northeastern regions have been active, giving rise to unstable atmosphere circulations, northern cold airflows met with southern warm airflows, bringing about heavy rains, Sun said.

Global warming was also behind the extreme weather in northern China. The rise in temperatures has caused higher humidity and stronger meridional circulations, which has increased the possibility of rain, he said.

Moreover, as rates of temperature rises differed in different areas, the speed of the westerly belt was slowed and air circulations were strengthened, providing the conditions for extreme weather, Sun said.

Editor: Chen Zhi
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