Ground to Cloud and Cloud to Ground Lightning Flashes: A Comparative Study

Abstract

Since cloud to ground lightning °ashes are the most common type of earth flashes, it has received much attention with reference to obtaining the engineering parameters such as the electric charge moment (QL, where Q is the total charge lowered by the lightning °ash) rate of rise of current and peak electric current. Measurements made in various parts of the world were used to arrive at a standard that could be set for both land and airborne systems, devices and vehicles. In this paper we report the use of a well tested model of earth °ash, namely the transmission line model, and explore the discharge process of the electric charges, as depicted in the voltage collapse shown as well as the return stroke currents for cloud to ground flashes and ground to cloud flashes. Amongst the significant results we report are the much higher rate of rise of currents we observed for ground to cloud (upward) lightning flash return stroke, and the much deeper collapse of the electrostatic potential, and electric charges, in the case of ground to cloud return stroke. In contrast, the cloud to ground °ash collapse of the electrostatic charge is not so severe, thus allowing for more subsequent °ashes to occur over the same lightning channel.