Distribution characteristics of cloud particles and cloud condensation nuclei during haze/fog events in Shijiazhuang.

Cloud droplets and cloud condensation nuclei(CCN) over Shijiazhuang area,Northern China,were measured based on airborne instruments during May to October,2009.The data obtained from 7 flights were used to analyze the characteristics of number concentration,liquid water content,the mean diameter and the effective diameter of cloud droplets,as well as the spatial,temporal and spectral distribution of CCN in stratocumulus and altocumulus clouds under foggy/hazy weather conditions.The results show that the number concentration of cloud droplets was in the 102 orders of magnitude high under foggy/hazy weather conditions,and that the sizes of cloud particles measured at higher levels were larger than that at lower levels.The mean values of the cloud water content calculated from the droplet size spectra were between 0.03 to 0.14g/m3,and the mean value of CCN concentration averaged between the surface and at 600m high was 3034cm-3(for supersaturation of 0.3%).The size distribution of CCN was fitted with a power law function and was shown of continental type.The results also show that clouds had a scavenging effect on CCN,but the CCN concentration could be increased remarkably due to present of an inverse layer.