Preliminary study of coupled oxidation-reduction reactions of included ions in growing ice crystals

Cloud chamber studies have demonstrated coupled oxidation-reduction reactions of included ions in free-falling ice crystals growing in a supercooled liquid water cloud. These reactions are hypothesized to occur as a consequence of preferential ion separations which take place at the interface between growing ice and the liquid layer at the growing crystal surfaces, followed by electron transfers to establish system neutrality. Oxidations of sulfide ion to sulfate ion and of halide ions to higher valence species have been documented. Reductions of silver ion to metallic silver and of sulfate ion to lower valence species have also been documented in systems of appropriate ion compositions. Similar reactions have been reported to occur during the freezing of bulk dilute solutions of ammonium and/or halide salts.