Wildfires can become so intense that they produce thunderstorms. This phenomenon of fire-triggered thunderstorms is called pyroCbs, which is short for pyrocumulonimbus clouds.
Pyrocumulonimbus clouds are also known as cumulonimbus flammagenitus. Cumulonimbus flammagenitus stems from the Latin words meaning “flame” and “created from.”
NASA refers to pyroCbs as the “fire-breathing dragon of clouds“.
While the exact physics behind these fire-triggered thunderstorms is still unclear, pyroCbs are triggered by the uplift of ash, smoke, and burning materials via super-heated updrafts. Wildfire flames release enough heat and moisture into the atmosphere to produce thunderstorms. As these materials cool, clouds are formed that behave like traditional thunderstorms but without the accompanying precipitation.
These pyroCbs produce dry lightening which can trigger further wildfires.
Scientists are studying how climate change, which is driving larger and more intense wildfires, are also creating a higher frequency of pyroCbs.
Fire-triggered thunderstorms are being generated in places that have never experienced this phenomenon before such as Texas, Portugal, South Africa, and Argentina (Related: Smoke from Australian Wildfires Reaches Atmospheric Highs). pyroCbs are particularly destructive due to the tornado-strength vortexes that are produced.
A single pyroCb can send particles as high as 10 miles into the lower stratosphere according to Dr. Glenn K. Yue, an atmospheric scientist at NASA Langley Research Center in Hampton, Virginia.
One of the Largest pyroCb Events Seen in the United States
On September 6, 2020, NASA’s Suomi NPP satellite was able to measure the “largest (if not the largest) pyroCb events seen in the United States,” according to Dr. Colin Seftor, Atmospheric Scientist at Goddard Space Flight Center in Greenbelt, Maryland.
The pyroCb cloud was triggered by the the Creek Fire which began in the Big Creek drainage area between Shaver Lake, Big Creek, and Huntington Lake in California. Sensors onboard the Suomi NPP satellite measured aerosol index values indicating this was one of the largest pyroCb events ever recorded.
Reed, J. (2020, October 16). California’s Creek fire blasts smoke into the stratosphere. NASA Applied Science. https://appliedsciences.nasa.gov/our-impact/news/californias-creek-fire-blasts-smoke-stratosphere
Struzik, E. (2019, January 24). Fire-induced storms: A new danger from the rise in wildfires. Yale E360. https://e360.yale.edu/features/fire-induced-storms-a-new-danger-from-the-rise-in-wildfires