Journal ArticleCorona Discharges Glow on Trees Under ThunderstormsMcFarland, P J [Department of Meteorology &amp; Atmospheric Science The Pennsylvania State University University Park PA USA] (ORCID:0000000245402324); Brune, W H [Department of Meteorology &amp; Atmospheric Science The Pennsylvania State University University Park PA USA] (ORCID:0000000216094051); Miller, D O [Department of Meteorology &amp; Atmospheric Science The Pennsylvania State University University Park PA USA] (ORCID:0000000310173979); Jenkins, J M [Department of Meteorology &amp; Atmospheric Science The Pennsylvania State University University Park PA USA] (ORCID:0000000233309640)nullnull<title>Abstract</title> <p>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 ∼10¹¹photons at 260 nm, corresponding to electrical currents of ∼1 μA, 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 emitted by trees, subtle tree leaf damage, and limited thunderstorm electrification.</p>Wiley2026-02-2810668184Geophysical research letters5340094-8276https://doi.org/10.1029/2025GL1195912323203CoronatreesthunderstormNational Science Foundation