Last week, the The US Naval Research Laboratory held a press conference in 2021, in which scientists reported on the “smog thundercloud” that erupted in 2021. Catastrophic wildfire, Exacerbated by catastrophic climate change, Had a rash Fire Cumulonimbus Over the western United States and Canada, it is called pyroCb in scientific terminology.
David Peterson, a meteorologist at the research laboratory, said at the Zoom press conference: “You can think of them as huge chimneys, gathering the smoke released by the fire into thunderstorms.” “You can imagine this extremely dirty Thunderstorms, all these smoke particles can condense water.”
However, unlike a typical thunderstorm, the resulting water droplets tend not to grow large enough to rain. “But it is a cloud that can produce a lot of lightning,” Peterson added. These clouds can then pass through the landscape, triggering new wildfires as they move.Therefore, fires can not only spread by themselves by throwing embers in front of the main line of fire (the reason why California wildfires are so deadly is partly due to seasonal strong winds. Push them at incredible speed), it can also produce so much hot, rising smoke that it essentially absorbs the atmosphere and ignites more fires for it. This is an out-of-control self-proliferation machine.
Fire cumulonimbus plumes can also stimulate the wildfires that produce them. When hot air rises from the fire, the air close to the ground will rush in to fill the gap, thereby increasing the wind speed on the ground. But because pyroCb is a thundercloud, it will also produce downdrafts along with the updrafts, resulting in extremely irregular wind behavior near the surface. Basically, if you expect the wildfire that produces pyroCb to behave in a reasonable way, traversing the landscape in the prevailing wind, then you have another thing.
These pyrCbs can be hugeThe hotter the wildfire burns, the more rising air it produces. Peterson said: “They push the smoke upwards at extremely high speeds, so they spray smoke at an altitude higher than the cruise altitude of the jet.” “So we may be talking about 50 or 60,000 feet.” In fact, he said , The smoke actually rushes into the next layer of the atmosphere, the stratosphere, which is higher than where weather usually occurs. Peterson added that a pyroCb plume formed in British Columbia in 2017 lasted 10 months in the stratosphere.
Once all these smoke aerosols enter the stratosphere, they will have conflicting effects. Because they can actually block the sun, they cool the landscape below. However, the plume itself will absorb solar energy, warming the local air, thus forming “hot bubbles”. This creates an atmospheric engine that drives the smoke cycle, which scientists call a “vortex”. Mike Fromm of the Remote Sensing Department of the U.S. Naval Research Laboratory said at a press conference: “So, the small engine incident caused by putting smoke into the stratosphere caused its own stratospheric weather.” A new discovery, but it is very real. We have now seen it in many cases.”
At the end of June, Peterson and Fromm tracked one of the largest coke plumes in North America’s history. The formation of these clouds may not be a mistake, but a feature of the climate becoming abnormal. “We have been setting off a wave of pyrCb activities in North America-there have been activities almost every day in recent days,” Peterson said. “This pyroCb outbreak is actually the latest in a series of pyroCb outbreaks that we have seen globally in recent years.”
This The terrible bushfire season of 2019-20 For example, Australia produced 38 such plumes in just a few days.In all places, Siberia has been breeding them Its scenery is warm, Dry out, and igniteDaniel Swain, a climate scientist at the University of California, Los Angeles, said: “I want to say that in the past few fire seasons, there were many of them.” “There may be several different reasons.”