the series of electrical processes by which charge is transferred along a channel of high ion density between electric charge centers of opposite sign (a) within a thundercloud (cloud discharge), (b) in a cloud and on the earth?s surface (cloud-to-ground discharge or ground-to-cloud discharge), (c) within two clouds (cloud-to-cloud discharge), or (d) in a cloud and in the air below the cloud (air discharge)This definition last updated 06/30/2008