'An unworldly experience.' Why scientists flew into firestorm clouds this wildfire season

As wildfires grow bigger and hotter in many parts of the world, researchers have embarked on an airborne mission to learn more about the severe storm clouds that sometimes form over the most intense blazes.

"Firestorm" clouds, or pyrocumulonimbus (pyroCb), can pump as much smoke into the stratosphere as a volcanic eruption. They are responsible for a range of extreme weather, from lightning to firenadoes, but much about their inner workings is unknown, which makes their behavior difficult to predict. That's a danger for the residents and emergency crews who might be in harm's way.

WATCH: How massive wildfires in the West spread harmful particles across North America

This summer, a team of scientists led by NASA, the U.S. Naval Research Laboratory (NRL) and the National Center for Atmospheric Research (NCAR) got an up-close look at these clouds by flying a pair of aircraft over and into wildfire smoke plumes with an array of measuring instruments.

"Being able to both sample inside the plumes and the clouds and above — and relating what we're seeing — that's something that we've never been able to do before," said John Yorks, a research physical scientist at NASA's Goddard Space Flight Center.

The multi-year mission, called INSPYRE (Injected Smoke and Pyrocumulonimbus Experiment), aims to gather real-time data from active wildfires to help scientists better understand what makes these clouds tick and how they affect the atmosphere.

"You can think of INSPYRE as a really well-organized storm chase," said David Peterson, a meteorologist at NRL and the mission's principal investigator. "We're basically chasing storms that are triggered by wildfires."

Peterson said the team's first deployment this summer, which wrapped up last week, was "incredibly successful."

Flying into the firestorms was "kind of an unworldly experience," Peterson recalled. "It's a really dark, almost orange hue when you go through the cloud. Also, because of the huge amount of smoke that's been pushed upward, you can often smell that on board for a little bit."

"We were able to get into the tops of the smoke as it was released by these clouds. We were even able to sample the tops of the clouds themselves," he said.

Here's what to know about pyrocumulonimbus clouds and what researchers hope to learn from the INSPYRE mission.

How a firestorm is born

In hot, dry and windy conditions, with abundant fuel, some wildfires can generate a dense plume of smoke that rapidly carries water vapor and smoke particles high into the atmosphere. As the water vapor cools and condenses, a pyrocumulonimbus cloud forms and spreads out at the top of the plume.

Animation by Wesam Sorour/PBS News

"PyroCbs act as giant chimneys and push lots of smoke upward in the atmosphere," Peterson said.

Firestorm clouds can generate their own weather that in turn creates more hazardous conditions on the ground, researchers say. Dry lightning strikes can ignite new fires miles away and strong downdrafts create storm-force winds that endanger firefighters attempting to contain the blaze.

"Everything is amplified by orders of magnitude over a regular storm or fire event," said Michael Fromm, a meteorologist at NRL.

Both the smoke and the cloud itself make it difficult to even see the flames that are generating the fire, which can hinder evacuation efforts, he said.

"Predicting when they're going to occur so we don't have to evacuate people in those dreadful conditions is something that's very important," Fromm said, adding that weather forecasters and first responders "all need to know a little bit more about these extremely unpredictable fire events."

More commonly seen in North America and Australia, where massive wildfires occur more frequently, the phenomenon is also cropping up in Europe as that continent grapples with record heat. France reported its first pyroCb cloud in the country's recorded history in July.

READ MORE: French wildfire created country's 1st recorded pyrocumulonimbus cloud, igniting more fires

"These events in recent years have become very large," Peterson said. "Over the past decade or so, there have been a few events that have pushed enough smoke to high altitudes that it actually rivals or exceeds what we would expect from a large volcanic eruption."

That includes Australia's devastating Black Summer bushfire season of 2019-2020 that produced a "super outbreak" of pyroCb clouds. One of the largest of those smoke plumes traveled around the world and persisted in the Southern Hemisphere for more than a year, Peterson said.

A glimpse inside the unknown

Many aspects of firestorm clouds remain a mystery, which can make them particularly challenging for researchers to model and forecast.

"We've only been studying them for 15, 20 years," Yorks said. "That's not a long time in our research world, so there's still a lot to understand about how they form, why they form and how they connect with the meteorological conditions in the regions where they're forming."

INSPYRE builds on a proof-of-concept study by NASA and NOAA from 2019, Peterson said, one of the only other times scientists have gotten up close to firestorm clouds.

While satellites can observe pyroCb clouds from the top down, up until now there's been a lack of "real, in situ data" from within them, said Ziming Ke, assistant research scientist at the Desert Research Institute.

Aerosol index image of California's 2020 Creek Fire, showing some of the highest values recorded from a pyrocumulonimbus cloud in the U.S. Image by C. Seftor/NOAA/NASA

Ke, who led a 2025 study that was the first to successfully simulate firestorm clouds using an Earth system model, compared the phenomenon to a smoky house that you can't see inside. Understanding what types of aerosols are present and whether droplets or ice crystals are forming within the clouds is helpful information for forecasting, he added.

"If we have some sort of ice cloud organization, we can predict there will be lightning at some point," Ke said.

As wildfire smoke rises through the pyroCb chimney and interacts with moisture in the atmosphere, it also takes on different properties than smoke on the ground, Peterson said.

"If we want to be able to forecast smoke properly, being able to identify which fires produce pyroCbs and how high that might reach into the atmosphere is step one," he said. "But then if we want to be able to account for the effect of the smoke in terms of heating or cooling different layers of the atmosphere, we have to know exactly what the size of the particles are."

One of the aerosols that researchers hope to understand better from the INSPYRE flights is black carbon — soot from fires that absorbs solar radiation and generates heat — and how much of it gets sucked up into pyroCb clouds.

"Does all this turn into rain and come out the bottom, or does some of this survive up into the upper atmosphere? And then once it's up in the upper atmosphere, what does that do to the chemistry of the layer?" Anne Perring, a chemistry professor at Colgate University, said in July as the mission kicked off.

"So we're really interested to just see how efficiently black carbon moves through the system and at the top," she said.

Flying through a chimney of wildfire smoke

As wildfires burned across the Western U.S. this summer, the INSPYRE team tracked the storms that were generated in a coordinated effort of at least 150 people on the ground and in the air.

"Each aircraft has its own science team associated with it. There's a ground team with truck-mounted radar and lidar that's also involved along with a forecast effort," Peterson said.

NASA's Earth Resources-2 plane carried remote sensors high above the fires, while NCAR's Gulfstream V flew through the smoke below as inlets pulled air from outside into onboard instruments that measured chemicals, aerosols and water vapor.

A view from the cockpit of the Gulfstream V aircraft overlooking a pyrocumulonimbus cloud during the INSPYRE mission, on Aug. 7, 2026. Photo provided by NASA

"We have the ER-2 flying overhead kind of as a steerable satellite, so that's above all the weather," Peterson said. "At the same time, we have the GV that's pulling outside air in, and so it needs to get up close."

Those direct, on-site observations will help modelers create a vertical profile of what's going on inside the firestorms and how they evolve with the fires, said Ke, who is working on improved fire and weather models to better predict the phenomenon in the future.

"I think it will help the whole community," he said.

Crews spent the final week of this year's deployment chasing a smoke plume that originated from a massive firestorm cloud in Siberia, crossed the Pacific Ocean and reached as far as Idaho, Peterson said.

"This is by far the most comprehensive sampling of something like that," he said, adding that he thinks the data they gathered will help researchers make enormous advancements that current weather forecast models can't account for.

Now that the flights have ended for this year, Peterson said the team will start analyzing the data in more detail.

"What did we capture really well? What do we still need to capture in our deployment next year?" he said. "And then next year, we'll do this again to try to fill any gaps that we have."