How does lightning interact with the earths electric field?
On the scale of a single thunderstorm, lightning is a discharge–a means of releasing the tremendous electrical energy built up by the storm. But on a global scale, thunderstorms actually separate charge. Lightning and other storm-related electrical features act to maintain a permanent potential of some 300 kilovolts between the earth’s crust, which is negatively charged, and the ionosphere (well above 30 miles, or 50 kilometers), which is positively charged. In between, the slightly conductive lower atmosphere allows current to flow between the two regions. Were it not for the constant recharging from thunderstorms, the earth-atmosphere potential would disappear in a mere five minutes.
