Lightning

The primary source of lightning discharge is a thundercloud, in which the electrification of various cloud particles occurs. This chapter explains how a thundercloud is formed and how the electrification occurs in the thundercloud. There are several theories for explaining the mechanism of cloud electrification. The chapter also explains the graupel-ice mechanism, which is capable of explaining the tripolar charge structure in the thundercloud and is thought to be the dominant electrification mechanism. It then describes the cloud lightning discharges and cloud-to-ground lightning discharges. Next, the chapter outlines features of lightning return-stroke electric and magnetic fields, and then gives mathematical expressions for calculating lightning return-stroke electric and magnetic fields. It also discusses lightning surges on an electric power system and a telecommunication system. Finally, the chapter reviews measures for protecting these systems against lightning surges.