Free electrons get accelerated upward and get kicked up into a hyperenergetic state, massively relativistic, and at some point they bang into atoms in the tops of the storm towers with such energy that they produce gamma rays which in turn produce positrons—antimatter. The positrons have opposite charges, so they get accelerated downward. The cycle repeats, up and down, and at some point you get a burst of gamma rays that is seriously dangerous—you could get a lifetime’s worth of hard radiation exposure in a flash.”
