NO_<i>x</i>Production in Lightning

Abstract

The rate of odd nitrogen (NOx) production by electrical discharge through air was theoretically and experimentally estimated to be ∼6 × 1016 NOx molecules per joule. The theoretical treatment employed a cylindrical shock-wave solution to calculate the rate of NOx production in high temperature reactions. The limits obtained were experimentally verified by subjecting a regulated air flow to electrical discharges followed by a measurement of NOx production using chemiluminescence. These measurements also indicated that water vapor content has no detectable effect on the NOx production rate. Our results imply that lightning is a significant source of NOx, producing about 30–40 megatons NOx-N per year and possibly accounting for as much as 50% of the total atmospheric NOx source.