These two photographs, taken from an Oregon Air National Guard F-15C on July 31, give a close look at a developing pyrocumulus cloud above the Oregon Gulch fire, a part of the Beaver Complex fire on the Oregon/California border.
Pyrocumulus clouds—sometimes called “fire clouds”—are tall, cauliflower-shaped, and appear as opaque white patches hovering over darker smoke in satellite imagery. Pyrocumulus clouds are similar to cumulus clouds, but the heat that forces the air to rise (which leads to cooling and condensation of water vapor) comes from fire instead of sun-warmed ground. Under certain circumstances, pyrocumulus clouds can produce full-fledged thunderstorms, making them pyrocumulonimbus clouds.
Here’s a satellite view of the fast-moving fires. More than 100,000 acres (400 square kilometers) were charred in a few days as fires raged through forests and grasslands in northern California. NASA’s Terra satellite captured this image on August 2, 2014. Red outlines show where MODIS detected high surface temperatures associated with active burning.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons.