During thunderstorms, a large electrical field between the ground and clouds develops. High conducting points, such as the tops of towers built specifically to draw lightning, are usually surrounded by a corona discharge. When this discharge is quenched (such as when there is an abrupt change in the field under the clouds), an electrical leader starts from the top of the tower. If this occurs when the clouds are beginning to discharge, this leader initiates a lightning strike. By using laser beams to create plasma channels at the tops of the towers, Ushida's group has, to the best of their knowledge, reported the first laser-plasma-triggered lightning.
