Analysis of Characteristics and Formation Conditions of Regional Radiation Fogs in Guizhou
By investigation of the visibility data at 08:00 over Guizhou Province and surface 08:00 weatherTcharts from 1971 to 2008, a total of 382 regional radiation fog processes are selected to analyze the spatial and temporal distribution characteristics of regional radiation fogs in Guizhou. Using the surface and upper air weather charts at 08:00 of 93 radiation fog processes during the 10 years, the corresponding weather circulation conditions are researched. Using the surface and radiosonde meteorological data, the meteorological elements of influencing the formation of radiation fogs are studied. The results show that regional radiation fogs in Guizhou mainly happened in mid-autumn and winter, more frequently in the east than in the wesi.of Guizhou, and there was an evenly distributed pressure field while regional radiation fogs occurred. There are four upper air circulation conditions of regional radiation fog: northwest flow type, southwest flow type, subtropical high type and straightly west flow type. There are four meteorological conditions beneficial to the formation of regional radiation fog: low surface wind speed, high surface humidity, significant radiation cooling at night and temperature inversion at surface layer, and the vertical air with upper-layer dry and lower-layer wet.