During a research flight on August 11, 2026, over the Sand Creek fire in Montana, NASA captured images of a pileus cloud atop a pyrocumulus, a fire-generated cloud formed by the wildfire.
These observations were made as part of the INSPYRE (Injected Smoke and Pyrocumulonimbus Experiment) campaign aboard the ER-2 research aircraft equipped with the MASTER (MODIS/ASTER Airborne Simulator) airborne simulator.
The pileus cloud, a thin veil-shaped cloud resembling a cap, formed when the rapid ascent of hot air caused by the fire forced a layer of moist air at altitude to rise, cool, and condense its water vapor.
Neil Lareau, co-investigator of the INSPYRE project, explains that the pyrocumulus acts like a mountain, forcing moist air upward to form this characteristic cloud, which is a sign of particularly vigorous convection.
The images clearly show the circular pileus cloud above the column of smoke and water vapor, with areas of active fire and burned terrain identified through infrared imaging.