In all the explanations of how global electric circuit on Earth works, I've always encountered statements like "thunderstorms generate ionospheric potential" (which is about 250 kV). E.g. here: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2009JA014758

But how is that possible? Thunderstorm (or, more specifically, a lightning strike) is inherently a discharge rather than a generator. It's the breakdown of an abstract capacitor rather than the charging of it. For all intents and purposes, thunderstorms should reduce any potential difference that exists around them rather than sustain it.

Can somebody explain, what actually drives the upward current that is observed above thunderstorms? Surely it cannot be lightning itself, so what then?

(I'm perfectly aware that there is also a downward current in fair weather; but the same question remains - where is the generator that causes it?)

  • $\begingroup$ You are aware of charge separation in updrafts due to friction of water on oxygen molecules? It's not that what you're asking about, or is it? I may misunderstand.. $\endgroup$ Sep 14 '19 at 17:00
  • $\begingroup$ Yes. I am aware of that. But how can it drive a large scale (50-80 kilometers in length) electric current? It's not like it's the ionosphere rubbing against the crust and both are getting charged, right? So where is this current coming from? Why do the positives go up in the thunderstorm, while negatives go down, and nothing stops them from doing that (even lightning)? $\endgroup$
    – Eugene B.
    Sep 14 '19 at 18:08
  • $\begingroup$ Well, if there is no other field shielding it, then EM-fields are far-reaching forces. But that's not a complete answer. $\endgroup$ Sep 14 '19 at 18:47

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