Weather Words: Pyrocumulonimbus

Pyrocumulonimbus is a variation of a fire cloud, they are formed by intense updrafts from large fires and can take on characteristics similar to thunderstorms, such as gusty winds, lightning, and even tornadoes.

Pyrocumulonimbus clouds develop from pyrocumulous clouds, which form from smaller fires heating the surrounding air, forcing it to become less dense than the surrounding air and rise. As a fire grows, it heats more air. As the air near a fire becomes very hot and expands, the decrease in density causes the air to rise violently until a pyrocumulonimbus cloud is born.

Pyrocumulonimbus clouds can then rise tens of thousands of feet until reaching the top of the troposphere, the lowest level of the atmosphere where weather occurs. In some cases, pyrocumulonimbus clouds can even push into the stratosphere, the layer of the atmosphere above the troposphere.

The name pyrocumulonimbus comes from the Latin words “nimbus,” which is Latin for dark cloud, "pyro," which stands for fire, and "cumulo," which stands for heap or pile.

Tornadoes formed from fires are often referred to as "firenadoes" or "fire whirls."

Hayden Marshall is a meteorologist intern and First-Year-Master’s Student at the Georgia Institute of Technology. He has been following weather content over the past three years as a Storm Spotter and weather enthusiast. He can be found on Instagram and Linkedin.