Electric Skies - Thunderstorms and Lightning

EW: The global circuit is the framework set up by the Earth, the ionosphere and all the electrified weather in the insulating air layer in between. Electrified storms pump current from the Earth to the upper atmosphere and thereby maintain a 250 kV voltage difference between Earth and ionosphere - a giant spherical capacitor. The same pair of concentric conductors (Earth and ionosphere) make up the electromagnetic waveguide that contains the Earth's Schumann resonances which we discussed earlier. Both aspects of the global circuit - the 'DC' version with the 250 kV ionospheric potential and the 'AC' version with Schumann resonances, provide integrated estimates of global weather measurable at single locations on the Earth's surface. This situation provides a natural framework for studying global change. For several years we have been intrigued with the idea of monitoring temperature variations with the global circuit, following well recognized local observations indicating that, on average, warmer conditions favor more lightning. Within the past decade, both the 'DC' and 'AC' global circuits have been examined for sensitivity to temperature on a variety of time scales - the diurnal, the intraseasonal (20-60 days), the semiannual, the annual and the El Nino time scale - all with some indication of a correlation with temperature and with a sensitivity of some tens of percent per degree centigrade. The global circuit sensitivity to global warming is still highly uncertain, the available record lengths are short and the natural variability of the global circuit is large. This work is now in progress along with notable gains in our ability to measure the global circuit, a capability that has greatly lagged our conceptual understanding.

FS: We need batteries and motors to produce electricity, how is lightning produced in our atmosphere?