Abstract: A system utilizing ionization produced by beams from laser and laser-like devices to pre-determine the course of stepped leader and lightning channel development, thereby affording protection of life and property. The applications of such a capacity to harmlessly discharge thunderclouds include forest fire prevention, protection of aircraft, protection of missiles and spacecraft (particularly at time of launch), protection of electric power transmission and distribution networks, protection of communication networks, and (to the extent that Vonnegut's electrical theory of tornadoes may be valid) reduction of the destructive force of tornadoes.