Based on the conventionally observational data and automatic weather station data,the synoptic background,temperature and humidity conditions,atmospheric stratification feature of a wide urea of continuously heavy fog event in Shaanxi Province during November 12-17th 2007 were analyzed.The main conclusions were as follows:the 500 hPa circulation at mid-latitude was northwest flow,and the ground was con trolled by the equal pressure filed,which were favorable for the radiation fog;late Shaanxi was in the isobar dense area of the high-pressure,which formed the front fog;1-4 m/s surface wind and weak vertical movement in lower level were the dynamical conditions of the fog weather;the configurations of big relative humidity at lower level and small relative humidity at middle level constituted water vapor condition of the fog;stable atmospheric stratification and the lower temperature inversion,hindered the low-level moisture diffusion upward,were conducive for the occurrence of the fog.%利用常规探测资料、自动站资料,对陕西2007年11月12～16日大范围持续性大雾产生的天气背景、温湿条件和大气层结等特征进行分析.结果表明,前期500 hPa陕西为西西北气流,地面为均压场控制,辐射降温有利于近地层水汽凝结成雾;后期陕西处于高压前部等压线较密集区,形成锋前雾;1～4m/s的地面风速、低层弱的垂直速度是这次雾形成的动力条件;上干下湿的高低空配置是大雾发生的水汽条件;大气层结稳定,低层有逆温、稳定少动的暖盖,阻碍低层水汽向上扩散,有利于大雾发生.
展开▼
