Pennsylvania State University researchers have directly observed and measured an electrical phenomenon called corona on sweetgum, loblolly pine and other tree species under thunderstorms in several U.S. states.

Most people know about lightning and the havoc it wreaks on forests. They do not know about the weak electrical glow, called a corona, that is thought to form on tree leaves under thunderstorms. Using an ultraviolet-sensitive instrument, Pennsylvania State University researchers have now directly observed and measured this electrical phenomenon on sweetgum, loblolly pine and other tree species under thunderstorms in several U.S. states.