As people grow more and more comfortable performing scientific experiments in the sky, we continue to learn more about ever-mysterious lightning. A new study in the journal Science provides the latest insight into the illusive electrostatic discharges; outlining evidence supporting the idea that they are indeed a “detergent of the atmosphere.”
The Smithsonian Magazine reported on the new study, which researchers at Penn State authored. William H. Brune, a professor of meteorology at the university, led the researchers as they looked back on data a NASA jet measured in storm clouds over Colorado, Oklahoma, and Texas in 2012.
During its June 2012 run, NASA’s jet specifically measured two molecules in the storm clouds: hydroxyl radicals (OH) and hydroperoxyl radicals (OH2). Scientists refer to the former molecule as an atmospheric “detergent” because it reacts with, and decomposes, pollutants. Hydroxyl also plays a key role in removing greenhouse gases—like methane and ozone—from the atmosphere.
According to the study, the 2012 data points to lightning directly generating hydroxyl; as opposed to the previous model of the atmospheric phenomenon, which only evinced lightning’s production of the radicals indirectly. “We [were] surprised by the extreme amounts of OH and HO2 generated in thunderstorm anvils and cores,” Brune told Inverse. “They are orders of magnitude larger than any previous atmospheric HO2 or OH measurement,” he added.
Brune and his colleagues say that both visible and “subvisible” lightning produce the molecular detergent. (The subvisible lightning isn’t visible to the naked eye, nor any sort of camera.) The scientists also say that the NASA jet specifically detected the subvisible discharges of the radicals in the anvil regions of the thunderstorms; that is, the icy, windy, electrified clouds at the tops of the storms (above).
Based on this data, the researchers speculate that 2-16% of global atmospheric oxidation—a.k.a. atmosphere “cleaning”—is due to lightning-generated hydroxyl radicals. The hydroperoxyl radicals, likewise, may also significantly contribute to atmospheric cleansing of pollutants. Although the researchers caution these results are “highly uncertain” because they don’t know if these measurements apply to the rest of the globe. The only way to know for sure, they say, is to perform more aerial experiments in the midst of storms.