Analyses of a microphysical response to the seeding in two cases of artificial fog dissipation

Two field experiments were performed in order to dissipate the fog at Wuqing District of Tianjin in November and December of 2009. Hygroscopic particles were seeded to dissipate fog droplets on 6-7 November, 2009. Liquid nitrogen (LN) was seeded into the natural supercooled fog in the experiments of 30 November-1 December, 2009. Significant response was found after seeding. Significant changes were observed in the microstructure of fog in the field experiments. The of fog droplet changed dramatically; it increased first and then decreased after seeding. Remarkable variation also was found in the Liquid Water Content (LWC) and in the size of fog droplet. The Droplet Size Distribution (DSD) of fog broadened during the seeding experiments. The DSD became narrow after the seeding ended. After seeding, the droplets were found to be at different stages of growth, resulting in a transform of DSD between unimodal distribution and bimodal distribution. The DSD was unimodal before seeding and then bimodal during the seeding experiment. Finally, the DSD became unimodally distributed once again.