According to the Department of Energy’s Pacific Northwest National Laboratory, thunderstorms could be contributing to global warming due to their ability to capture and retain heat. If true, environmental scientists may have to drastically adjust their climate models in order to take this in account.
In a press release, Jiwen Fan from the Department of Energy said that the heat strengthens storm clouds, causing their tops to spread out high in the atmosphere and capture heat, especially at night. “Global climate models don’t see this effect because thunderstorm clouds simulated in those models do not include enough detail,” says Fan. “The large amount of heat trapped by the pollution-enhanced clouds could potentially impact regional circulation and modify weather systems.”
Thunderstorm clouds are known as deep convective clouds and are an important part of the climate cycle. Due to their size, they reflect a lot of the sun’s energy back into space, whilst trapping rising heat and returning evaporated water back to the Earth in the form of heavy rain. Past studies have shown that clouds can capture pollution when it’s windy leading to bigger clouds. The pollution particles divide up the water droplets found in the cloud, which in turn leads to a higher number of smaller droplets that are too small to form into raindrops. Instead, they simply create larger, more vigorous convective clouds that last longer and absorb more water vapor.
The team studied two different types of storm systems for their report, including warm summer thunderstorms in southeastern China and cool, windy frontal systems on the Great Plains of Oklahoma. Creating simulations of the storms, the researchers were able to study how the clouds developed while changing the conditions such as wind speed and air pollution. What they found was that during warm summer thunderstorms, pollution led to stronger storms with larger anvils. When compared to clouds that developed in non-pollution areas, the team noticed that the warming effect dominated. They also noticed that the pollution-enhanced clouds also trapped more heat at night, leading to warmer nights.
“Those numbers for the warming are very big, but they are calculated only for the exact day when the thunderstorms occur,” says Fan. “Over a longer time-scale such as a month or a season, the average amount of warming would be less because those clouds would not appear everyday.”
via TG Daily