Scientists have known for decades that thunderstorms are often stronger where there are high concentrations of aerosols–airborne particles too small to be seen with the naked eye. Lightning is more common along sea routes, where cargo ships emit particles into the air, than in the surrounding ocean. And the most intense thunderstorms in the tropics are brewing on dry land, where aerosol levels are high by both natural and man-made phenomena.
Now MIT scientists using idealized cloud dynamics simulations have found that low clouds with high aerosol concentrations are less likely to release water as rain. Instead, their water evaporates, creating a wet layer that facilitates the rapid rise of air through the atmosphere in the form of strong updrafts and causing storms.
“After you establish this relatively low humid layer in the atmosphere, you have a bubble of warm, humid air that can act as a seed for a thunderstorm,” says Tristan Abbott, graduate student, who co-wrote an article on research with his assistant professor of atmospheric science Tim Cronin. They say this “moisture entrainment” mechanism, as they call it, could be incorporated into weather and climate models to help predict how thunderstorm activity in an area might vary with aerosol levels. changing.
“It’s possible that by cleaning up pollution, places will experience fewer storms,” Cronin says.