Thin, tropical clouds cool the climate

STOCKHOLM, Sweden, Aug. 17 (UPI) -- Climate models have failed to account for mid-level clouds in the tropics. New satellite analysis of tropical clouds has revealed their ubiquity, as well as their underappreciated cooling effect.

Thin, tropical clouds form at an altitude of roughly three miles, often near convective clouds. The latest analysis suggests they help cool the climate.

"Their cooling effect could be as large as the warming induced by high cirrus clouds," Quentin Bourgeois, a climate researcher and postdoctoral associate at Stockholm University, said in a news release.

The role of clouds in climate models -- and the roles of different cloud types -- remains one of the most challenging variables for climate scientists as they try to calculate the precise effects of global warming.

As the new research emphasizes, different types of clouds have different effects on the sun's energy. Predicting how a warming climate will alter the makeup of Earth's clouds is a complicated process.

"To bridge our gaps in knowledge about thin mid-level clouds we used space-borne lidar instruments that provide detailed information on the vertical distribution of clouds," Bourgeois explained.

Part of the challenge of crafting accurate cloud models is understanding their formation processes. Scientists are constantly improving their knowledge of cloud-formation variables, but there is much yet to learn.

Bourgeois and his colleagues, who published their latest research in the journal Nature Communications, hope the latest data will help explain how thin mid-level clouds form in the tropics.