Sparklers ⚡
"Coronae, which are weak electrical discharges, have long been hypothesized to form on trees under thunderstorms, though never directly observed, characterized, or quantified. "Using a newly developed instrument that measures ultraviolet emissions from coronae, the first direct observations and quantifications of coronae are presented for two trees under a thunderstorm in North Carolina. "Coronae moved sporadically among leaves on every tree branch in a narrow field of view while the thunderstorm was directly overhead. "Coronae emitted ∼10 11 photons at 260 nm, corresponding to electrical currents of ∼1 ΞA, derived from unique measurements relating corona intensity to tree electrical current. "Similar results across four additional storm intercepts from Florida to Pennsylvania give rise to a vision of swaths of scintillating corona glow as thunderstorms pass over forests. "Such widespread coronae have implications for the removal of hydrocarbons emitt...