How anvil plumes, massive tornadoes, and the ozone layer relate

Science & Technology

(WUTR/WFXV/WPNY-TV) – High Resolution supercomputer simulations that were developed at the University of Wisconsin are helping to understand an atmospheric phenomenon that can be seen with some of the most destructive tornadoes on Earth.

The name of this phenomenon is an anvil cirrus plume, which forms as an upside down U shape of cirrus clouds above the top of severe thunderstorms. They can indicate the imminent formation of large hail and damaging tornadoes as about 75 percent of thunderstorms with these plumes produce large hail or tornadoes. The plumes themselves are driven by another phenomenon known as a hydraulic jump. 

Under certain atmospheric conditions, air flows rapidly over a thunderstorm’s overshooting top, a dome-like shape above the storm. In simulations showing these anvil cirrus plumes, a thin, horizontal stream of fast moving winds (in excess of 200 mph) comes before the formation of the hydraulic jump. In the jump’s turbulent wake, ice and water vapor are injected into the stable middle layer of the atmosphere, known as the stratosphere, forming an anvil cirrus plume.

The stratosphere is typically a very dry layer in the atmosphere, and thunderstorms are a known mechanism for adding water to it. When water that makes up these anvil cirrus plumes is broken apart by solar energy, it ignites a chemical reaction that can destroy the Earth’s protective ozone layer. Researcher Leigh Orf with the UW–Madison Cooperative Institute for Meteorological Satellite Studies explained “In a warming climate… scientists are interested in how much water is injected into the stratosphere by thunderstorms because of the aggregate effect this has on stratospheric ozone”. He went on further to say that the simulations exhibited plumes pushing water deeper into the stratosphere which could have a more long-term climate impact.

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