8. Electric Currents in Lightning Flashes

The length of a lightning channel can be tens of kilometers long, and at each point on this channel there is a current flow that changes with time. Unfortunately, it is possible to directly measure only the current at the strike point of a ground lightning flash. When discussing the features of a lightning current, we are actually referring to the features of the lightning current at the strike point. In special cases the current can be measured at elevated strike points by recording the currents in lightning flashes striking airplanes in flight. It is important to note that the features of currents flowing at other points of a lightning channel could be different from that measured at ground level. The farther away the point of interest from the strike point, the larger the possible difference between the two currents. However, before giving the features of lightning currents at strike points, let us understand how the currents in lightning strikes can be measured.