Pyrocumulonimbus clouds produced by the Mullen Fire in Wyoming
GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed a series of pyrocumulonimbus (pyroCb) pulses emanating from the Mullen Fire in southeastern Wyoming on 19 September 2020. Each of the pulses exhibited 10.35 µm brightness temperatures of -40ºC and colder (shades of blue) — assuring the heterogeneous nucleation of all supercooled water droplets to form ice crystals, thereby meeting the criteria of a pyroCb.The coldest cloud-top infrared brightness temperatures were around -47ºC, which corresponded to altitudes near 11 km according to rawinsonde data from Riverton, Wyoming (below).