Distribution electrical conduction currents in the vicinity of thunderstorms

Abstract

A simple bipolar thunderstorm model, in which it is assumed that the atmospheric conductivity increases exponentially from the earth to a conducting layer high in the atmosphere, is proposed for the purpose of estimating the electrical conduction currents in the vicinity of the storm. Calculations based on the model indicate that the separate measurements on electrical structure of thunderstorms, atmospheric conductivity, and upward conduction currents from storms are mutually consistent within the limits of uncertainty of the measurements. The computed current density at the surface of the earth at distances of several tens of kilometers from the storm is very much smaller than the normal fair-weather current density, but is very sensitive to the value assumed for the height of the upper conducting layer. The latter result suggests that, if the maximum in conductivity observed at about 19 km altitude is a persistent feature of the atmosphere, the disturbance of normal atmospheric conduction produced by storms may be observed at distances of the order of 100 km. This mechanism is suggested as an explanation of disturbed atmospheric electrical conditions observed many tens of kilometers from weather fronts.