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.