The Electrical Nucleation of Ice in Supercooled Clouds

Abstract

An electrified wire suspended in a supercooled cloud generates a jet of ice crystals only when there is ice on the wire. On a clean platinum wire no ice forms an the wire down to ?20C, but if the wire is coated with a hydrophobic material, ice nucleates on the wire at temperatures as high as ?5C. The electrical field of the wire is found to be insufficient to promote ice nucleation by enhancing the free energy difference for the transformation of bulk supercooled water to ice. A mechanism is proposed to explain how the electric field induces an otherwise inert substrate to generate the let of ice crystals.