午夜欧美大片免费观看,欧美激情综合五月色丁香,亚洲日本在线视频观看,午夜精品福利在线

Fog is one of the most severe weather events in Beijing in winter, and restrains the diffusion of air pollutants. During heavy fog days from 30 November 2002 to 4 December 2002, air pollutants were greatly retained by the wind shadow, low convergent zone, and conditional stability. The air was polluted heavily. The variation characteristics of air pollutants and the evolvement and characteristics of the related synoptic processes are analyzed.