Aerosols strengthen storm clouds, create longer and more intense storms

Lawrence Goodwyn

The accumulation of aerosols can cause storm clouds to linger longer and generate stronger storms.

Most people associate aerosol with a can of hairspray, spray paint or keyboard cleaner. However, aerosols can be any solid or liquid suspended in a gas. In regard to the atmosphere, aerosols are collections of cloud droplets around which other cloud droplets can form, bringing together large masses of clouds.

UT geosciences professor Rong Fu and geosciences postdoctoral student Sudip Chakraborty worked together to assess the link between aerosol particles and clouds causing varying weather conditions. The team discovered that aerosols can withhold a cloud’s rainfall and prolong the duration of cloud-cover over an area.

“Aerosols affect the lifetime of the storm by forming smaller droplets, making [the droplets] take longer to grow, and therefore delaying precipitation,” Fu said.  

Chakraborty said that when the humidity and wind chill rates are substantial aerosols can make the storm last an additional three to 24 hours.

Fu and Chakraborty gathered data from deep convective clouds in the Congo, Amazon and Southeast Asia. Deep convective clouds are expansive, dark and extremely tall storm clouds known for creating large thunderstorms and are prominent south of the equator.

Fu said that aerosols can either be natural, occurring in sea salts, desert dusts, forest fires or man-made, as in the burning of biomasses like wood, coal, and oil.

“Biomass-burning aerosols are a very important source of aerosols and are largely man-made, like in the Amazon and Congo where these fires are done by humans,” Fu said.

The team used two different satellites to collect data on clouds. They used a geostationary satellite, which flies very high and can only stay in one place, and a polar-orbital satellite that flies at low altitudes. The polar-orbital satellite produces high-resolution measurements of the clouds in the region, but can only do so twice a day because it moves with the Earth.

The team was not able to constantly monitor the clouds because of the limitations of the satellites. Chakraborty said he had to coordinate the data from both satellites to get a continuous measurement of the clouds.

While scientists have been studying the effects of aerosols on clouds for more than the past three decades, to their knowledge, Fu and Chakraborty are the first to show how aerosols affect the longevity of deep convective clouds.

Chakraborty said that the team next plans are to study the effects of aerosols on clouds in Europe and other northern locations and their exact rain rates in these regions.

“Since the level of aerosols in the tropics is increasing, clouds that should’ve been gone today, won’t even be gone the next day,” Chakraborty said. “There’s a lot of possible future implications of this, such as the issue of a loss of sunlight on the environment and radiation energy levels.”