“…One set of theories that does not primarily focus on microphysics includes ion convection (Grenet, 1947, Vonnegut, 1954, ion induction (Wilson, 1929;Whipple and Chalmers, 1944) and polarization charging (Elster and Geitel, 1913;Mason, 1972). Other theories are highly dependent on microphysics -water drop breakup (Simpson, 1909), splashing of water drops on ice (Workman and Reynolds, 1950), melting of ice (Dinger and Gunn, 1946), riming electrification (Reynolds et al, 1955;Takahashi, 1978a) and others.…”