California's Fires Are Creating Volcanic Clouds

Wes Siler, Outside on July 28, 2018

Three terrible wildfires are burning in California right now. And all three are more visually menacing than usual, thanks to a unique weather phenomenon the flames are creating. The fires are burning so hot that they're making their own pyrocumulus cloud systems, each up to five miles high. These clouds are also making firefighting efforts more difficult.

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.

Pyrocumulus clouds are more commonly seen above volcanic eruptions, which produce lots of steam. If you’ve ever seen an evil-looking cloud creating dry lightning above a volcano, that’s a pyrocumulus cloud. They’re colored black or dark brown by the volcanic ash, whereas ones created by wildfires are usually dark gray, due to the smoke and ash.

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