MIT: Warming Making Storms Stronger, Slowing Air Movement In Mid-Latitudes

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Scientists report that rising global temperatures, particularly in the Arctic, are redistributing the energy in the atmosphere: More energy is available to fuel thunderstorms and other local, convective processes, while less energy is going toward summertime extratropical cyclones -- larger, milder weather systems that circulate across thousands of kilometers. These systems are normally associated with winds and fronts that generate rain.

"Extratropical cyclones ventilate air and air pollution, so with weaker extratropical cyclones in the summer, you're looking at the potential for more poor air-quality days in urban areas," says study author Charles Gertler, a graduate student in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS). "Moving beyond air quality in cities, you have the potential for more destructive thunderstorms and more stagnant days with perhaps longer-lasting heat waves." Gertler and his co-author, Associate Professor Paul O'Gorman of EAPS, are publishing their results in the Proceedings of the National Academy of Sciences.

A shrinking gradient

In contrast to more violent tropical cyclones such as hurricanes, extratropical cyclones are large weather systems that occur poleward of the Earth's tropical zone. These storm systems generate rapid changes in temperature and humidity along fronts that sweep across large swaths of the United States. In the winter, extratropical cyclones can whip up into Nor'easters; in the summer, they can bring everything from general cloudiness and light showers to heavy gusts and thunderstorms.

EDIT

Since 1979, they found the energy available for large-scale extratropical cyclones has decreased by 6 percent, whereas the energy that could fuel smaller, more local thunderstorms has gone up by 13 percent. Their results mirror some recent evidence in the Northern Hemisphere, suggesting that summer winds associated with extratropical cyclones have decreased with global warming. Observations from Europe and Asia have also shown a strengthening of convective rainfall, such as from thunderstorms.

EDIT

https://www.sciencedaily.com/releases/2019/02/190218153218.htm

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