Silver iodide aerosol

The easiest model to treat theoretically is the sphere, and many colloidal systems do, in fact, contain spherical or nearly spherical particles. Emulsions, latexes, liquid aerosols, etc., contain spherical particles. Certain protein molecules are approximately spherical. The crystallite particles in dispersions such as gold and silver iodide sols are sufficiently symmetrical to behave like spheres. 

One may effectively control the stability of atmospheric aerosols by spraying concentrated solutions of hygroscopic substances, such as calcium chloride, or solid substances, such as silver iodide and solid carbon dioxide. These substances cause condensation of water vapor (or the formation of small ice crystals in supercooled clouds), and result in precipitation. Analogous means can be used to dissipate fog. 

Schaefer (1966) reported the activation of large numbers of ice nuclei on the addition of trace levels of iodine vapor to car exhaust (containing lead oxide nanoparticles) at temperatures from —3 to —20°C in the laboratory. The formation of lead iodide was concluded to have a seeding effect similar to that of silver iodide particles (Vonnegut, 1947), which had been used in an attempt to artificially modify cloud properties and enhance precipitation. Consequendy this method was proposed as a means to remove harmful aerosol formed in polluted urban areas, and also in artificial weather modification. However, the development of unleaded fuels, for which no similar ice nucleating ability was shown to occur in the presence of iodine (Hogan, 1967), provided a better long-term solution to this problem. 

DeMott, P.J. 1995. Quantitative descriptions of ice formation mechanisms of silver iodide-type aerosols. Atmos. Res. 38 63-99. 

Furrer, M., Cripps, R. Validation of Impair 2 code using ACE test results from the Radioiodine Test Facility (RTF). Proc. 3. CSNI Workshop on Iodine Chemistry in Reactor Safety, Tokai-mura, Japan, 1991 Report JAERI-M 92-012 (1992), p. 329-344 Furrer, M., Gloor, T. Effects of P , y radiolysis on cesium iodide solutions in contact with simulated silver metal aerosol. Proc. Specialists Workshop on Iodine Chemistry in Reactor Safety, Harwell, England, 1985 Report AERE R 11974 (1986), p. 193-199 Gauvain, J., et al. Iode 2.0 User manual. Report SEAC/91/04 (1991)... 

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