Electric Whirl

When brought near the dome of a Van de Graaff generator, the whirl spins rapidly in a direction that is away from the points. The electrons escaping from the dome to the spokes ionize the air at the sharp points. Since the spokes are continuously charged, the ionized air particles are repelled and the spinning results from an equal and opposite force reaction. Even if it is given an initial spin in the opposite direction, it will stop and reverse.