Abstract

Gigantic jets are the clearest manifestation of direct electrical coupling between tropospheric thunderstorms and the ionosphere. They are leaders^{1, 2, 3} that emerge from electrical breakdown near the top of thunderstorms⁴ and extend all the way to the lower edge of the ionosphere near 90-km altitude⁵. By contrast, blue jets⁶ and other related events^{7, 8} terminate at much lower altitudes. Gigantic jets have been observed from the ground^{5, 9, 10} and from orbit¹¹. Some seem to be consistent with an upward-propagating negative discharge of 1,000-2,000 C km total charge moment change ⁹, but others have not been connected to distinguishable electromagnetic signatures¹⁰. Here we report simultaneous low-light video images and low-frequency magnetic field measurements of a gigantic jet that demonstrate the presence and dynamics of a substantial electric charge transfer between the troposphere and the ionosphere. The signatures presented here confirm the negative polarity of gigantic jets⁴ and constrain the lightning processes associated with them. The observed total charge transfer from the thunderstorm to the ionosphere is 144 C for the assumed channel length of 75 km, which is comparable to the charge transfer in strong cloud-to-ground lightning strokes.