Last week The U.S. Naval Research Laboratory held a press conference in 2021, at which scientists reported the outbreak of a “cloud of thunder smoke” in 2021. Catastrophic forest fires, exacerbated by catastrophic climate change, produced a rash of pyrocumulonimbus plumage over the western United States and Canada, in the scientific language known as pyroCb.
“You can think of them as huge chimneys, sucking in the smoke that the fire emits into the storm,” said David Peterson, a meteorologist in the research laboratory, during a press conference Zoom. “You can imagine this extremely dirty storm with all these smoke particles on which water can condense.”
Unlike typical thunderstorms, the water droplets that form do not tend to become large enough to fall in the form of rain. “But it’s a cloud that can produce a lot of lightning,” Peterson added. These clouds can then move through the landscape, leading to new ongoing fires. Thus the flames cannot spread just by throwing embers in front of the main line of fire (California forest fires are partly so deadly due to strong seasonal winds that push them with incredible speeds), can produce so much hot smoke that rises that it essentially recruits the atmosphere to ignite more fires for it. It escaped a self-proliferating machine.
Pirocumulonimbus feathers will also energize the forest fire that spawned them. As the hot air moves away from the fire, air near the ground rises to fill the void, exaggerating wind speeds on the surface. But since pyroCb is a thundercloud, it also creates a descent along with that upward current, creating an extremely irregular wind behavior near the surface. Basically, if you expect a pyroCb spawning fire to behave in a rational way, marching through a landscape with prevailing winds, there is one more thing ahead of you.
And these pyroCbs can be huge. The harder the fire burns, the higher the air rises. “They push the smoke upwards at extreme speeds, so they inject smoke at altitudes above the cruising altitude of the jet planes,” Peterson said. “So we’re potentially talking about an altitude of 50,600 meters.” In fact, he says, the smoke will actually pour into the next layer of the atmosphere, the stratosphere, above where the weather usually occurs. Peterson added that one pyroCb that was created in British Columbia in 2017 created a plume that existed in the stratosphere for 10 months.
Once all these smoke aerosols enter the stratosphere, they can have a contradictory effect. Because they can actually block the sun, it will cool the landscape below. But the plume itself will absorb the sun’s energy, heating the air locally creating a “heat bubble”. This creates an atmospheric engine that drives the circulation of smoke, which scientists have called “swirling”. “So this small engine event, created by the release of smoke into the stratosphere, leads to its own stratospheric time,” said Mike Fromm, a remote research department at the U.S. Maritime Research Laboratory, during a press conference. “It’s a completely new discovery, but it’s very real. And we have seen that in many cases. ”
In late June, Peterson and Fromm tracked one of the largest pyroCb feathers ever recorded in North America. Creating this type of cloud may not be a mistake, but a feature of a bizarre climate. “We’ve been in a wave of piroCb activity in North America – almost daily activities in recent days,” Peterson said. “This pyroCb outbreak is actually the latest in a series of pyroCb epidemics we’ve seen in the world in recent years.”
The terrible season of raging fires 2019-20 for example, 38 of these feathers were produced in Australia in just a few days. Siberia, of all places, also spawned them as his landscape is warming, dries up and fire. “There have been a striking number of them, I’d say, in the last few seasons of fires,” says UCLA climate scientist Daniel Swain. “And there’s probably a few different reasons for that.”