The Nucleation of H2SO4-H2O Solution Aerosol Particles in the Stratosphere

Abstract

The homogeneous- and heterogeneous-heteromolecular nucleation of H2SO4-H2O solution droplets in the stratosphere is investigated and order-of-magnitude nucleation rates are evaluated. The heterogeneous processes considered are nucleation (i) onto soluble particles, (ii) onto flat insoluble surfaces, (iii) onto spherical insoluble particles and (iv) onto ions. The relative importance of the various nucleation mechanisms is determined for conditions assumed to correspond to 18 km altitude. Under the assumed conditions the heterogeneous nucleation rate onto insoluble particles is shown to be about 1069 times larger than the homogeneous nucleation rate and 1057 times larger than nucleation onto ions.