Organic molecules help fatten cloud-making water droplets
Better size estimates could help improve climate forecasts
IN THE CLOUDS Many of the water droplets that make up clouds get a size boost from carbon-containing molecules that assemble on the droplets’ exterior, new research suggests.
Jan Kraus/Flickr (CC BY 2.0)
For many cloud-forming water droplets, it’s what’s on the outside that matters.
By making their own clouds, scientists have discovered a new way that fat water droplets take shape. Carbon-containing molecules envelop the exterior of developing droplets and reduce surface tension, thereby allowing more water to condense onto the drop. This effect results in droplets that are about 50 percent wider than previously expected, the researchers report in the March 25 Science.
Heftier water droplets are more apt to form clouds, says study coauthor Kevin Wilson, a physical chemist at Lawrence Berkeley National Laboratory in California. Understanding how growing droplets assemble into colossal clouds is a big deal, he says, because climate scientists currently struggle to accurately reproduce cloud formation in their climate change simulations (
