A systematic field observation of the haze and fog was conducted and last 45 days in the northern suburbs of Nanjing during the winter of 2017. In this study, an advection radiation fog event from December 30 to 31 was forced on, and the meteorological elements, the macroscopic and microscopic features of fogs and aerosols were analyzed. It was found that the continuous cooling caused by cold advections and the long-wave night sky radiation dominated the development of fog, and the enhancement of short-wave radiation leaded to the fog dissipation. There was an explosive growth in the fog, where the liquid water content increased by three orders of magnitude from 10^-4g/m³ to 10^-1g/m³ within 17 minutes, and the increasing number concentration of fog droplets contributed 67% to the explosive growth. There was an obvious characteristic of uneven distribution in the strong fog. In addition, a new phenomenon of nano-scale aerosols accumulation in the strong fog was observed after sunrise, where the increment speed of the number concentration of the aerosols with diameters from 10nm to 50nm reached 2817cm^-3/h. The following parts were examined to discuss the reasons for the cumulative event, including the secondary aerosol generation, i.e.,gas-to-particle and gas-to-liquid conversions of SO₂, and aerosols transport process, i.e., the local aerosols accumulation from human activities and a potential turbulence transport mechanism in fogs.