EFFECTS OF SOLUBLE SALTS IN CLOUD ON ICE NUCLEATION─A LABORATORIAL STUDY

Two sets of laboratorial experiments are carried out to study the effects of soluble salts in cloud on ice nucleation processes.The cold stage is used for the individual drops freezing and 2m3 cloud chamber for the cloud droplets population experiments.The results show that drops (or droplets) containing NaCI, NH4Cl and (NH4)2SO4 with concentrations typically found in natural cloud do not act upon ice nucleation at temperature warmer than -18℃.However, they seems to have slight effects on ice crystal producing number and crystal aggregation.The experiments also show that high concentration of ammonium salts can obviously increase the freezing temperature of drops which contain AgI.When AgI is used to seed the cloud containing ammonium salts, the ice crystal production could increase about 1-2orders of magnitude at temperature -6℃ and -10℃ respectively comparing with seeding pure water cloud.