The following are the main characteristics of the general atmospheric circulation in December 2010. There was one weak polar vortex center in the Northern Hemisphere, which was extending to middle latitudes in East Asia, guided cold air going down south. The circulation presents a four wave pattern in middle high latitudes. The subtropical high is more easterly than normal years. The south branch trough is slightly stronger than normal years. The monthly mean precipitation (18.0 mm) is 83.7% above normal, but is 80% less than normal in North China, central west Huang Huai Plain etc., and increases drought in these areas. There were four cold air processes affecting most areas of China, including part of Northeast China, and Inner Mongolia and northern Xinjiang suffered snow disasters.