When lightning strikes, it’s not just dramatic, it’s chemical. Turns out, every bolt releases nitrogen oxide, the same stuff your car coughs out in traffic. Scientists just tracked it from space.
Now, for the first time, scientists at the University of Maryland have tracked this storm-born chemical from space. Their satellite sleuthing reveals how lightning contributes to air pollution, and also sparks reactions that help clean the atmosphere.
Using NASA’s TEMPO instrument, scientists tracked thunderstorms as they rolled across the eastern U.S., not after the fact, but live, in action. Instead of guessing what happened, they watched the chemistry unfold in the sky.
TEMPO usually scans North America every hour from 22,000 miles up, but in this experiment, researchers zoomed in, capturing nitrogen dioxide from each storm every 10 minutes. It’s like switching from snapshots to a high-speed video of pollution in motion.
UMD Atmospheric and Oceanic Science Research Professor Kenneth Pickering said, “This is the first time this kind of research has been conducted at such a temporal frequency. Thunderstorms evolve rapidly. They often build up, intensify, and die within an hour. These short interval observations give us better snapshots of what actually happens during a storm.”
Associate Research Scientist Dale Allen said, “With this experiment, we’re able to count the number of lightning flashes as they occur using data from NOAA’s Geostationary Lightning Mapper satellite instruments, and in turn, get a more accurate idea of how much nitrogen dioxide each flash of lightning produces during a storm and how long it sticks around afterward. This information will help researchers improve existing climate models and enhance our understanding of how lightning can affect the air we breathe.”
When lightning strikes, it heats the air to extreme temperatures, hot enough to split nitrogen and oxygen molecules apart. These fragments quickly recombine into nitrogen oxides (NOₓ), the same pollutants that come from car engines and burning fossil fuels. These gases help form ozone, which can be harmful near the ground.
Globally, lightning accounts for about 10–15% of all nitrogen oxides in the atmosphere. That’s much less than human-made sources, but here’s the twist: lightning injects these pollutants high up in the atmosphere, where they’re especially good at triggering ozone formation.
Car exhaust dumps pollutants close to the ground, where they directly affect the air we breathe. Lightning, on the other hand, sparks pollution high in the atmosphere, right where ozone is most potent at trapping heat and warming the planet.
But the story doesn’t end up there. That high-altitude ozone can hitch a ride on shifting air currents and descend to the surface, sometimes impacting air quality far from the original storm. And in summer? It’s a perfect storm: hotter temperatures supercharge ozone production, making lightning’s impact even stronger.
Allen added, “Lightning’s effects on climate during the summer season are comparable to anthropogenically created nitrogen oxides, which is why we wanted to study storms during June.”
Lightning isn’t just a fiery streak of pollution; it’s also a surprising force for atmospheric cleanup. When it strikes, it not only creates nitrogen oxides (NOₓ), which contribute to ozone and warming, but also sparks the formation of hydroxyl radicals. These radicals are like the atmosphere’s detergent, breaking down methane and other greenhouse gases that linger in the air.
Thanks to NASA’s lightning experiment, scientists uncovered how this chain reaction unfolds: lightning produces NOₓ, which then helps generate hydroxyl radicals. This insight helps researchers better understand the chemical choreography happening during storms.
“From past studies by our group and others, we believe that each flash of lightning creates about 250 moles of nitrogen oxides in the sky on average,” Allen said. However, that value is uncertain, and the production by individual flashes varies by at least an order of magnitude. “We believe that when storms get more intense, lightning flashes get shorter and produce less nitrogen oxide per flash. This study will give us a chance to prove that. Understanding how the footprint of lightning will change in a world of intensifying weather extremes is essential to formulate climate models for the future.”
According to scientists, their TEMPO experiment has potential real-world impacts on daily life.
Gases produced by lightning can travel on long “conveyor belts of moving air” and influence air quality far from where storms originally occurred, Allen noted. Occasionally, lightning also contributes to ground-level ozone, a primary component of smog that can trigger asthma and other respiratory issues in humans.
“For people living in mountainous areas like Colorado, this information can be essential as lightning does make a significant contribution to surface ozone at higher terrain altitudes,” Pickering said. “It could make a difference in how meteorologists predict air quality during and after storms in such regions.”
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