Pollution is leading thunderstorm clouds to capture heat, increasing global warming in a way that climate models have failed to take into account. It strengthens them, causing their anvil-shaped tops to spread out high in the atmosphere and capture heat, especially at night, says Jiwen Fan of the Department of Energy’s Pacific Northwest National Laboratory.

“Global climate models don’t see this effect because thunderstorm clouds simulated in those models do not include enough detail,” said Fan. “The large amount of heat trapped by the pollution-enhanced clouds could potentially impact regional circulation and modify weather systems.” Thunderstorm clouds – known as deep convective clouds – are an important part of the climate cycle. They reflect a lot of the sun’s energy back into space, trap heat that rises from the surface and return evaporated water back to the surface as rain.