Global lightning activity (~50 discharges per second)

At any given moment there are on the order of 2,000 active storms on Earth, which together produce approximately 50 lightning discharges per second. This value is a long-term average; the instantaneous global rate fluctuates roughly in the range of 44-100 discharges per second according to the time of day and season Heckman 1998.

It is precisely this high and persistent frequency that is the reason the SR can exist as a stable, continuous phenomenon. If lightning struck only occasionally, the cavity would lose its energy between discharges and the resonance would break up into isolated flashes. At dozens of discharges per second, however, their contributions overlap and create a continuous resonance "background".

Measuring the SR therefore provides a global, integrated estimate of the planet's total lightning activity — unlike local detectors, it captures the contribution of practically all storms at once Heckman 1998.