Lightning is changing the atmosphere in surprising ways

Lightning isn’t just a dramatic flash in the sky during a summer storm – it’s also a surprising source of air pollution.

Each lightning strike creates nitrogen oxides – polluting gases also found in car exhaust. These gases shape air quality and influence the climate in ways scientists are only now beginning to track in real time.

With help from a powerful satellite, researchers at the University of Maryland have finally started capturing what lightning is really doing to our air.

A view from 22,000 miles up

A high-powered NASA satellite called TEMPO has been watching Earth from 22,000 miles above. Normally, it tracks air pollution every hour. But for a few days in late June 2025, researchers ran a special experiment.

The team had TEMPO collect data every 10 minutes to follow thunderstorms moving across the eastern United States. This gave scientists a rare chance to catch storms in action – not just after they happened.

“This is the first time this kind of research has been conducted at such a temporal frequency,” said Professor Kenneth Pickering.

“Thunderstorms evolve on a rapid basis. They often build up, intensify, and die within an hour’s time. These short interval observations give us better snapshots of what actually happens during a storm.”

Lightning’s effect on the atmosphere

Research scientist Dale Allen explained that with this experiment, the team is able to count the number of lightning flashes as they occur using data from NOAA’s Geostationary Lightning Mapper satellite instruments.

Allen said this provides 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,” noted Allen.

How lightning pollution forms

When lightning strikes, the heat is intense – hot enough to split apart nitrogen and oxygen molecules in the air.

The fragments recombine into nitrogen oxides, the same kinds of gases that come from burning gasoline or diesel. These gases are key players in forming ozone, a major air pollutant.

“Lightning globally makes up 10 to 15 percent of total nitrogen oxides released into the atmosphere,” Pickering said. “Human pollution is much greater, but what’s important to consider is that lightning releases nitrogen oxides at much higher altitudes, where it can be more efficient at catalyzing the production of ozone.”

While tailpipes pollute the air near the ground, lightning-generated pollution happens much higher. That matters because ozone formed up there has a stronger warming effect.

Sometimes, that pollution gets dragged down to the surface, affecting air quality hundreds of miles away. This happens more often in summer, when high heat speeds up ozone production.

“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,” Allen explained.

Lightning can be helpful

But it’s not all bad news. Lightning also creates something helpful: hydroxyl radicals. These tiny molecules act like the Earth’s cleaning crew, breaking down harmful gases like methane, a major greenhouse gas.

“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,” noted Allen.

“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.”

From mountain towns to city streets

What happens in a thunderstorm doesn’t stay in the thunderstorm. Gases released by lightning don’t just hang around – they travel. Winds in the upper atmosphere can carry them far away from where the storm happened, sometimes dropping them close to the ground.

“For people living in mountainous areas like Colorado, this information can be very important 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.”

Improving climate models

Although the TEMPO data is still being analyzed, it’s already certain that this experiment will allow researchers to untangle what pollution is human-caused and what is naturally occurring.

Currently, there’s a lot of uncertainty surrounding how much nitrogen oxide any given lightning flash actually emits. This satellite data provides researchers with the raw information they need to calculate that out, and how altering weather patterns may change the balance.

“We want to use this high-frequency data to narrow the major uncertainties in our current climate models,” Allen said.

“With better data comes better predictions, and potentially better ways to protect our health and environment from both natural and human-made pollution.”

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