The circulation background and characteristics of meteorological element distribution are ana- lyzed on a wide spread radiation fog that occurred in January 2010 over the Central China area. Observation and simulation of the wide spread radiation fog over Hunan are investigated by using a new generation of high-resolution Weather Research and Forecasting （WRF） Model. The results show that there are two ob- vious inversion layers occurring in the evolution process of the radiation fog. One is the subsidence inver- sion formed by the high-altitude systemic northerly airstream, which is located near 700 hPa with the sta- ble atmospheric stratification, and thus low-le.vel water vapor can not be propagated upward, and therefore provides high humidity conditions for the fog formation. The other is the radiation inversion formed from the surface cooling effect of radiation, which is the main factor for the formation and development of this fog. However, for the dissipation of the fog the main cause is the surface heating by solar shortwave radia- tion after sunrise and heat transportation. In addition, it shows that there are better simulation results by using WRF model when T213 data are used as the initial conditions instead of NCEP reanalysis. Theoverlap zone of the maximum U value below 900 m with large inversion ≥5℃corresponds well with the fog. At the north of the rivers and lakes, moreover after high ridge changed into high rear sector near the surface, the advection fog appears likely due to the effect of water vapor transport by low-level southerly flow. There is a gap of the near-surface layer of elements between the simulation from WRF model and ob- servations, and the assimilation of observation data must be considered in the simulation.%利用观测资料分析2010年1月华中一次大范围辐射雾过程的环流背景及气象要素分布特点。发现：本次大雾过程有两层较明显的逆温层，高空系统性偏北气流形成下沉逆温，位于700hPa附近，使大气层结维持稳定，低层水汽不能上传，为大雾生成提供高湿环境条件；地面辐射冷却作用形成近地辐射逆温层，是辐射雾形成和发展的主要因素，而日出后太阳短波辐射对地面的加热和热量湍流输送是白天辐射雾消散的重要原因。利用WRF模式进行模拟实验，发现用T213资料作为模式的初始和边界条件模拟近地层气象要素，较NCEP再分析资料有一定优势；900m以下U大值区与最大逆温≥5℃重叠区与雾区对应较好；河流湖泊北侧在地面由高压脊转高压后部后，在低空偏南气流水汽输送作用下，出现辐射雾转平流雾可能性较大；WRF模式模拟的近地面层要素结果和实况有所差距，必须采用观测资料同化改进。
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