Abstract:According to routine surface meteorological data, upper air sounding data and environmental pollutant observation data from 1998 to 2010 in Hangzhou, we did a comprehensive analysis of the haze characteristics and formation mechanism under the main synoptic situations, the typically meteorological elements as well as environmental pollution. The results indicate that the high pressure weather situation has a significant effect on haze in Hangzhou, while cyclone and easterly weather situation are less likely to occurring of haze. Neutral stratification plays a leading role in atmospheric stability under haze weather, the frequency is up to 54.3%. The frequency of haze under inversion conditions at 08:00 BT is higher than that at 20:00 BT, the average inversion strength under haze is higher than no haze weather, the inversion thickness, the maximum inversion strength and maximum thickness on average are lower than those of no haze weather. The concentrations of pollutants of PM10, SO2 and NO2 were decreased by 33.3%, 20.0% and 18.2% respectively on no haze days compared to haze days. With the increase in haze levels, the concentration of different pollutants also increases. Particles is one of the main reasons for reducing visibility. In addition, Hangzhou special terrain environment plays a role in leading to the occurrence of haze. Above results are significant to understand the occurrence of haze weather and develop the alarming and forecasting work.