Researchers at Pacific Northwest National Laboratory in Richland, Wash., have found that aerosol pollutants make summertime thunderclouds larger. They also discovered that these anvil-shaped clouds can help warm the atmosphere.
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Flickr Creative Commons: Pleroma
RICHLAND, Wash. – Researchers in the Northwest have found those giant, anvil-shaped thunderclouds you see looming in the distance may actually be getting bigger and stronger this summer, all because of aerosol pollutants.
Researchers at Pacific Northwest National Laboratory in Richland, Wash., have discovered these really big clouds trap more heat high up in the atmosphere. Scientist Jiwen Fan says summertime thunderstorms may actually contribute to a warming climate. That’s especially true in places where it rains a lot.
“In some places, especially in the southeastern U.S. and southeastern China, they have an afternoon shower every day,” Fan says. “So, in those kinds of situations, you will see a very significant effect on the atmosphere.”
Warm air pushes the aerosol high up into thunderclouds. The pollutants form droplets that make the cloud larger at the top, creating the anvil shape.
Oftentimes, climate research doesn’t take much information about clouds into account, Fan says. That’s because clouds are pretty small when considering a global-scale model. But, Fan says, the reaction between aerosol pollutants and thunderclouds can significantly change modeling results.
Scientists previously thought aerosols cooled the atmosphere. But Fan says that research left out important interactions between pollutants and thunderclouds.
“When you consider the aerosols’ effect on the clouds, the science may be changed,” Fan says. “Or the cooling effect they saw in the previous model will be much less.”
The researchers discovered that aerosol pollutants in summertime clouds caused warmer nights. Fan says she was surprised by the amount of heat the clouds generated in the upper atmosphere.
Researchers also studied thunderstorms that rolled in with cool fronts in the spring. They did not see the same warming effect during these systems as in the summertime thunderclouds.
Next, Fan will study warming trends with thunderclouds over an entire season and put these interactions into a global climate model to see changes overtime.
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