Lightning is, at its simplest, a spark of electricity that connects areas of positive and negative charges — within clouds or from a cloud to the ground, as seen here in the Arizona desert just before sunset. Photo © Marius Britt. Used with permission.

Lightning Strikes Twice, and Scientists Still Don’t Know What’s Going On

A pair of discoveries only reveals how clueless we are about how lightning starts and the “weird stuff” it does next.