Abstract:Based on the daily observation data of acid rain in Wuhan during 1990-2014, we studied the variation of acid rain and its relationship with rainfall intensity, wind, air mass source and pollutant source. The results indicated that the precipitation in Wuhan shows weak acidity and the annual mean pH is 4.86. The acid rain intensity showed an increasing trend in general but has tended to weaken since 2007. The annual mean electrical conductivity is 50.3 μS·cm-1 with a rise of 8.8 μS·cm-1 per decade. The pH value is lower in winter than in summer while the frequency and electrical conductivity are higher in winter than in summer. The conductivity and pH value of intense acid rain have an obvious negative correlation while a significant positive correlation is for non acid rain. The rainfall intensity is an important factor in the development of acid rain intensity and frequency, showing differences in different seasons. The intensity and the frequency of acid rain decrease when the wind speed at 1500 m height increases. Acid rain occurs more in southwest wind direction. The intense acid rain is mainly affected by acid rain from the south heavy air pollution area, and the external pollution sources by the atmospheric transmission contribute greatly to the intense acid rain in Wuhan. The sulphur dioxide content (SO2) in Wuhan tends to decline while the nitrogen dioxide content (NO2) tends to increase. The total concentrations of the two have presented a decreasing trend since 2000.