Gigantic jets of thunderbolts occur alongside lightning and head in the opposite direction of typical thunderbolts. This recorded thunderbolt however was strong enough to surpass the ionosphere and touch the edge of space. Itbis one of nature's finest mysteries that have been baffling scientists to date. 
While several researchers have been attempting to study this phenomenon, it has been difficult due to most of the instances of this reverse thunder having been captured accidentally- and mostly by civilians. The situation in Oklahoma that fateful day 4 years ago however was different as it occurred next to satellite networks and a lightning-mapping system. 
Research scientist at the Georgia Tech Research Institute and author of the paper: Upward propagation of gigantic jets revealed by 3D radio and optical mapping, Levi Boggs said, "We were able to see very high frequency sources above the cloud top, which had not been seen before with this level of detail. Using satellite and radar data, we were able to learn where the very hot leader portion of the discharge was located above the cloud.”