Extreme temperatures and wildfire currents, reaching many hellish proportions, have been marked in the Northern Hemisphere this summer. An unprecedented number of these have been burned through the margins, separating regular ignition from the more severe class known as firestorms, or pyrocumulonimbus (pyroCbs). Creating their own weather and preventing tropopause with a horrible push of smoke, pyroCbs are incredibly frightening, and their sudden outbreaks threaten that they may become more frequent in the future.
Mike Farm, a meteorologist at the U.S. Naval Research Laboratory, said: “We’ve seen to 75 to 80 pyroCbs in the Northern Hemisphere summer season, and that number seems to be higher than the previous season.” NRL), IFLScience has been explained. “I have to say quite emphatically although we can’t call it a trend. We don’t know if we have enough data to provide trend information.”
This lack of information is mainly due to the fact that, despite their staggering severity, it is not easy to detect pyroCbs. It is only over the last two decades or so that researchers have been able to identify them from satellite measurements of smoke in the stratosphere. “The word pyroCB didn’t even exist when I started in NRL in the mid-90s,” Fromm said. “What we’ve done is we’ve stumbled upon smoke in the stratosphere. We now need to identify and measure enough to see if the frequency of pyroCbs is increasing.”
As their other name implies “firestorm”, a pyroCbs is basically a thunderstorm caused by a fire. When a very large fire sends hot air into the air, it turns into clouds. If the atmosphere is unstable, the smoke can blow away, creating strong updrafts because cold air can fill the void below. These winds move the foot towards the fire, creating a reaction loop that causes more hot air to push towards the sky, causing the whole system to snowball. If the smoke reaches the plum stratosphere, it can cause a thunderstorm. At this point, it can be said that the fire is creating weather instead of turning the other way.
Once this happens, a fire acquires the title of pyroCb and becomes incredibly difficult to predict or control. The highest wildfire smoke recorded so far includes the Plum Australian New Year Super Outbreak (ANYSO) which spread between December 2019 and January 2020, sending 34 kilometers (21.1 miles) of smoke into the atmosphere – at the ozone level. The wind generated by pyroCbs of this size can exceed 160 kilometers per hour (100 miles per hour), throwing firebrands far away from the front of the fire, where they can ignite new fires.
