While intense fires burned in western Russia in the summer of 2010, a layer of smoke was spreading across the stratosphere, more than 12 kilometers above Earth’s surface. Few things have the power to send aerosol particles that high into the atmosphere. Until a decade ago, most scientists thought that only a volcano could do so. However, meteorologist Michael Fromm of the U.S. Naval Research Laboratory, has shown that large, fire-generated clouds can also inject particles high in the sky.
This image from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO) provides rare evidence that fire clouds can pull smoke into the stratosphere. CALIPSO sends a pulse of light through the atmosphere and records the light that bounces back to generate a profile of the atmosphere. This image shows the atmosphere over far northern Russia on August 1. The strongest return signal came from clouds. A layer of low clouds creates the dark red line along the lower part of the profile. One towering cloud reached into the stratosphere between 10 and 15 kilometers in altitude. A thin, even layer of aerosols caps the cloud and surrounds it on either side. Weather models and other satellite data reveal that this towering cloud formed over fires in western Russia on July 30, then drifted northward.
The top image, from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite, provides a true-color view of the same region. The red line indicates the path of the CALIPSO laser. The towering cloud is circular. It is surrounded by hazy, gray-white smoke.
The cloud is a pyrocumulonimbus cloud, a powerful thunderstorm that forms over large fires. Fires heat the air, pushing it high into the atmosphere where it can cool into clouds. Extreme fires can create towering clouds, pyrocumulonimbus clouds, that reach high enough to contain ice crystals. The ice crystals conduct electricity, forming a strong, dangerous thunderstorm. Pyrocumulonimbus clouds can produce strong winds and tornadoes that can fuel the fire’s rapid growth.
In the past decade, it has become clear that pyrocumulonimbus clouds also act like chimneys, pulling smoke into the stratosphere. Once in the stratosphere and above the weather, smoke can linger for a long time and spread around the globe. Aerosols can warm the stratosphere and cool the air below by absorbing energy from the Sun. However, this image shows one of the few pyrocumulonimbus clouds that have ever been documented, so it isn’t clear how often fires put aerosols in the stratosphere and how large an impact they have on weather and climate.
To see how Fromm used several NASA satellites together to document the pyrocumulonimbus cloud over western Russia, please see Russian Firestorm: Finding a Fire Cloud from Space on the Earth Observatory.
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