The Lightning Return Stroke Current: Formation, Propagation, Attenuation, and Dispersion Through the Lens of the Telegrapher's Equations

Abstract

The lightning return stroke is the most impactful aspect of a lightning flash. It has a transformative effect on the Earth system by igniting wildfires and by fixing nitrogen oxides in the atmosphere. It also has important detrimental impacts on societal infrastructure by causing billions of dollars in losses every year to power transmission and communications industries. The impacts of a lightning return stroke are due to its intense electrical current, which surges when lightning channels connect to a ground structure, and travels rapidly through those channels toward the cloud. The intense energy deposition in the atmosphere results in emissions across the entire electromagnetic spectrum. In this work, we present an overview on how to calculate the lightning return stroke electrical current using the Telegrapher's Equations, which describe the propagation of electrical signals guided by a conductor. This article has three main goals. First, it presents a tutorial overview on how to assemble a basic model of the lightning return stroke. Second, the article explains from basic principles the dominant features of the current wave, including: the genesis of channel-base current, and the subsequent propagation, attenuation, and dispersion. Third, it also serves as a literature review by drawing parallels between the return stroke properties inferred from the Telegrapher's Equations and those established in previous theoretical and experimental research.