Extreme oxidant amounts produced by lightning in storm clouds.

Brune, W H; McFarland, P J; Bruning, E; Waugh, S; MacGorman, D; Miller, D O; Jenkins, J M; Ren, X et al. · Science · 2021

basic_science · Level V

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Abstract

Lightning increases the atmosphere's ability to cleanse itself by producing nitric oxide (NO), leading to atmospheric chemistry that forms ozone (O<sub>3</sub>) and the atmosphere's primary oxidant, the hydroxyl radical (OH). Our analysis of a 2012 airborne study of deep convection and chemistry demonstrates that lightning also directly generates the oxidants OH and the hydroperoxyl radical (HO<sub>2</sub>). Extreme amounts of OH and HO<sub>2</sub> were discovered and linked to visible flashes occurring in front of the aircraft and to subvisible discharges in electrified anvil regions. This enhanced OH and HO<sub>2</sub> is orders of magnitude greater than any previous atmospheric observation. Lightning-generated OH in all storms happening at the same time globally can be responsible for a highly uncertain, but substantial, 2 to 16% of global atmospheric OH oxidation.