Yellowstone Fire and Pyrocumulus Clouds
January 25, 2009
The photo above shows towering pyrocumulus clouds from a distant wildfire in Yellowstone National Park, Wyoming. It was taken in midafternoon on August 1, 2008. These clouds formed as a result of the intense heat, and subsequent updrafts, associated with this fire. Large wildfires generate ash particles. These particles serve as condensation nuclei onto which the concentration of ambient atmospheric moisture readily occurs. Without a source of water vapor, either from the atmosphere or from the moisture in the vegetation evaporated during burning, pyrocumulus clouds will not form.