Pyrocumulus clouds, also known as “fire clouds,” are extremely rare cloud formations caused by rising heat and smoke from volcanoes, or as in the case in California right now, by raging wildfires. These fire clouds extremely fast-forming, can host their own lightning storms, and cause devastating wind.
In other words, the wildfire can create its own weather system. As Outside magazine explained:
Normal clouds are formed when the sun heats the earth’s surface, causing water to evaporate and rise into the atmosphere, where it cools and condenses into a cloud. This is a relatively slow process compared to the formation of a pyrocumulus cloud, where the intense heat of a huge wildfire burns the moisture out of the vegetation. This moisture then accumulates on smoke particles and rapidly condenses as it rises.
In California, passersby captured remarkable images of the wildfires sending up these cloud forms:
Northern California’s Carr Fire started on July 23 when a single vehicle caught fire and is still raging across almost 84,000 acres. Two other wildfires are raging in the state simultaneously; 60 uncontained large fires are burning throughout the country. Nearly 30% of the US is currently in drought. Meanwhile, deadly heatwaves have claimed dozens of lives in Canada and Japan, scorched landscapes across Europe, and sparked fires in Greece and Sweden.
These extreme heat conditions are not random, nor are they normal. The warming effects of climate change are making heatwaves twice as likely as they would be without that multiplier effect, according to a recent analysis by climate scientists studying the current northern European heatwave.
In California, no month has passed without a wildfire since 2012, “a stark contrast to previous decades, when fire officials saw the fall and winter as a time to plan and regroup,” according to the New York Times (paywall).
As such, it is becoming logically impossible to talk about these phenomena without mentioning climate change. As an editorial from California newspaper the Sacramento Bee put it on July 27: “This is climate change, for real and in real time. We were warned that the atmospheric buildup of man-made greenhouse gas would eventually be an existential threat.”
Correction: Due to an editing error, a previous version of this story mistakenly said the fires in California were raging over an area of 8,400 acres. In fact, it was 84,000 acres.