云中可溶性物质对冰核化影响的实验研究

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

用冷台冻滴和２ｍ３云室试验相结合的方法，研究了云中可溶性物质对冰核化的影响。实验结果表明，一般云中观测到的可溶性盐类气溶胶（如ＮａＣｌ、（ＮＨ４）２ＳＯ４等）在温度高于－１８℃时不易成为冰核。而高浓度的可溶性铵盐（如（ＮＨ４）２ＳＯ４，ＮＨＣｌ等）则能显著提高ＡｇＩ的成冰温度。（ＮＨ４）２ＳＯ４能使ＡｇＩ成冰晶数在－１０℃提高２个量级，－６℃提高约１个量级。该结果对人工催化技术有一定指导意义。

wo 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 NaCl, 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 prepucing 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- 2 orders Of magnitude at temperature - 6℃ and - 10℃ respectively comparing with seeding pure water cloud.