Ternary nucleation of H[sub 2]SO[sub 4], NH[sub 3] and H[sub 2]O.

A classical theory of the ternary homogeneous nucleation of sulfuric acid — ammonia — water is presented. For NH[sub 3] mixing ratios exceeding 1 ppt, the presence of ammonia enhances the binary (sulfuric acid — water) nucleation rate by several orders of magnitude. However, the limiting component for ternary nucleation — as for binary nucleation — is sulfuric acid. The sulfuric acid concentration needed for significant ternary nucleation is several orders of magnitude below that required in binary case. [ABSTRACT FROM AUTHOR]