Based on the aerosol data obtained from four flights which conducted on October 13 th and the 14 th in 2013 and the general weather data,the aerosol number concentration and the vertical variation of mean diameter before and after precipitation were analyzed in the region of Hebei province,as well as the particle spectrum characteristics in different levels. And the spectrum of aerosol particles in and on the bottom of stratiform cloud were tried to fitted. The results are as follows. 1) Before and during t...