Ground to Cloud Lightning Flash Currents and Electric Fields: Interaction with Aircraft and Production of Ionosphere Sprites

Abstract

This paper presents for the first time a case for the importance of ground to cloud (i.e. upward leader) lightning flash parameters for safety testing of aircraft-lightning interaction, protection of wind turbines, as well as the importance of cloud to ground radiated electric fields for indirect lightning-aircraft interaction and generation of electric discharges called sprites and halos in the ionosphere. Using a reliable electric circuit model of the transverse magnetic waves along the lightning channels, also called the return strokes, electric currents at ground level as well as cloud level are determined for both the cloud to ground lightning flash (downward, or earth flash) and the ground to cloud (or upward) lightning flash. It is shown that when an aircraft triggers lightning, the electric currents will be much more severe in current magnitude, rate of rise of currents and frequency spectrum than otherwise, and are more severe than the parameters observed for the usual and well monitored (and measured) cloud to ground (i.e. downward leader) flashes. The rate of rise of currents and the frequency spectrum of the ground to cloud lightning flash are also given here. The electric fields radiated by the lightning flashes that would appear in the ionosphere are presented for both the earth flash and the ground to cloud flash.