A PARAMETERIZATION OF CLOUD DROPLET NUCLEATION .2. MULTIPLE AEROSOL TYPES

A parameterization of cloud droplet nucleation for a single, log-norma lly distributed, aerosol type is generalized to the case of multiple a erosol types with differing size distributions and compositions. The p arameterization accounts for the competition between different aerosol types as cloud condensation nuclei, and the dependence of the competi tion on the number concentration, composition and size distribution of each aerosol type. Comparisons with detailed numerical solutions indi cate typical differences of 50% and 20% for the number fraction and ma ss fraction, respectively of aerosols activated for each type.