Robert also sent in a link to https://phys.org/print464237850.html … and asks, do tornadoes form in a process similar to lightning. That is, a downward propagating stepped leader and an upward moving streamer. Tornadoes might be a form of electrical discharge, he speculates. The link itself tells us that it has generally been thought tornadoes rotation largely begins in storm clouds, creating a funnel that travels downwards. New research shows tornadoes seem to form from the ground upwards. A bit of a turnaround.