Generation of Ice Nucleus Aerosols by Solution and Pyrotechnic Combustion
William G Finnegan
Combustion of acetone solutions of AgI and various chemical solubilizers and additives is used to generate ice nucleus aerosols for weather modification research, development and field use.
Nucleus chemical compositions have varied from AgI itself to 2AgI-NaI, and 2AgI-KI, to Ag(Cl)I and to Ag(Cl)I-x NaCI (where x has varied from 0.125 to 5), over time. Combustion of pyrotechnics to produce nucleus aerosols containing AgI is also widely used.
Silver iodide and silver chloroiodide “contact” nuclei have been the most often employed. More recent developments have led to the generation of Ag(Cl)I nucleants containing soluble salts, which function by rapid condensation-freezing mechanisms, rather than the cloud droplet “contact” mechanism.
These research and development efforts over a 50 years period have led to a better understanding of the relationships between ice nucleus compositions, activities, and the rates and mechanisms of ice crystal formation. Ice nucleus aerosols of optimum utility for field applications are now possible of generation.