Ternary nucleation of HSO4, NH3, and in the atmosphere

摘要: Classical theory of binary homogeneous nucleation is extended to the ternary system H2SO4-NH3-H20. For NH3 mixing ratios exceeding about 1 ppt, presence enhances H2SO4-H20 rate by several orders magnitude. The Gibbs free energies formation critical H2SO4-NH3-H20 cluster, as calculated two independent approaches, are in substantial agreement. finding that independ- ent relative humidity over a large range H2SO4 concentrations has wide atmospheric consequences. limiting component for is, case, H2SO4; however, concentration needed achieve significant nuclea- tion rates magnitude below required case. above solution (e.g., Scott and Cattell, 1979), expected facilitate (Coffman Hegg, 1995). In this paper, we present classical We compare predicted those H2SO4- H20 at levels NH3. One cau- should be noted regard other treatments based on theory. Whereas some labo- ratory measurements do not agree with predictions, others do; example, recent parameterization (Kulmala et al., 1998) agrees laboratory Viisanen al. (1997). Although molecular-based theories address limitations subject current atten- (Kusaka 1998), predictive molecular does exist. Thus still represents standard applica- against which will ultimately compared.