Julio Rubinstein, David Finkelstein, and James R. Powell proposed that ball lightning is a detached St. Elmo's fire (1964–1970). St. Elmo's fire arises when a sharp conductor, such as a ship's mast, amplifies the atmospheric electric field to breakdown. For a globe the amplification factor is 3. A free ball of ionized air can amplify the ambient field this much by its own conductivity. When this maintains the ionization, the ball is then a soliton in the flow of atmospheric electricity.