Pyrocumulus Clouds: Fire Clouds Produced by Volcanoes and Wildfires

Summary: Pyrocumulus clouds form in the troposphere, the lowest layer of Earth's atmosphere, as fire clouds produced by volcanoes and wildfires.

pyrocumulus clouds produced by wildfire in Yellowstone National Park: Brocken Inaglory, CC BY SA 3.0, via Wikimedia Commons

Pyrocumulus clouds are formed in the troposphere, the lowest layer of Earth’s five-layered atmosphere, by intense heat from the Earth’s surface. The cloud’s name reflects these origins: pyro (Latin: pyra, “funeral pile, pyre” from Ancient Greek: πῦρ, pûr, “fire”) and cumulus (Latin: cumulus, “heap, pile”). As low-level clouds, cumulus clouds float usually at altitudes of less than 3,300 feet (1,000 meters) within the six- to 11-mile (9.6- to 17-kilometer) upward stretch of the troposphere.

As residents of the layer mostly responsible for Earth’s day-to-day weather, cumulus clouds are responsive to such transforming triggers as convective instability via vertical movement of differently heated air parcels; dynamic instability via horizontal movement of air from such forces as Coriolis (deflection of movement to right in Northern Hemisphere, to left in Southern Hemisphere) and pressure gradients; and moisture.

Intensely heated air on the Earth’s surface rises via the process of convection from points of instability to a point of stability. Intense heat sources include such thermal phenomena as jet streams, nuclear weapon detonation, volcanic eruptions and wildfires.

The turbulent fluffiness of pyrocumulus clouds displays brown to gray to yellowish brown colors, often with fiery orange or red accents.

Are pyrocumulus clouds helpful or scary? Their helpfulness shows up as moisture in the cloud that may help to extinguish wildfires by condensing and falling as rain.

Pyrocumulus clouds also are scary. A large forest fire may encourage continued growth in its cloudy creation, leading to an extreme offshoot, a pyrocumulonimbus (Latin: nimbus, “dark cloud, rain cloud”) cloud of increased height. Pyrocumulonimbus clouds may reach altitudes of four to 13 miles (seven to 21 kilometers) as they puff up from the upper troposophere and tropopause to the lower stratosphere. Pyrocumulonimbus clouds unleash such monstrous complications as hail, lightning and tornadoes.

As products of hot scenarios, pyrocumulus clouds appear as photogenic, unforgettable rain-gifting saviors or pyrocumulonimbus-shapeshifting terrors in turbulent skies.

pyrocumulus clouds over Los Angeles, August 29, 2009, 19:41: Eric Chan from Hollywood, United States, CC BY 2.0, via Wikimedia Commons

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

pyrocumulus clouds produced by wildfire in Yellowstone National Park: Brocken Inaglory, CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Wildfire_in_Yellowstone_Natinal_Park_produces_Pyrocumulus_clouds1.jpg

pyrocumulus clouds over Los Angeles, August 29, 2009, 19:41: Eric Chan from Hollywood, United States, CC BY 2.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Pyrocumulus_clouds_over_LA.jpg