Lighting cleans the air even more than we thought.

Science News chases the storm chasers who found some surprising air-purifying oxidant chemicals in the wake of major lightning strikes:

Researchers knew lightning produces nitric oxide, which can lead to the formation of oxidants such as hydroxyl radicals. But no one had seen lightning directly create lots of these oxidants.

In May and June 2012, a NASA jet measured two oxidants in storm clouds over Colorado, Oklahoma and Texas. One was the hydroxyl radical, OH. The other was a similar oxidant called the hydroperoxyl radical, HO2. The combined concentration of OH and HO2 molecules, generated by lightning and other electrified regions of air, reached up to thousands of parts per trillion in some parts of these clouds. The highest concentration of OH previously observed in the atmosphere was a few parts per trillion. The most HO2 observed was about 150 parts per trillion.

“We didn’t expect to see any of this,” says William Brune, an atmospheric scientist at Penn State University. “We shelved the data … because it was just so extreme.” But lab experiments later showed that electricity really could generate such large quantities of OH and HO2, helping confirm these oxidant signals were real.

You can read more of their findings here, in Science.