NASA airborne laboratory flies through clouds to uncover surprising ocean link

Jetting through the sky in a NASA aircraft, scientists discovered that about one-third of fresh cloud seedlings that originate in the ocean vanish into veteran clouds before birthing new ones. The disappearance ultimately affects cloud factory assembly lines, lessening the output of baby clouds that could, one day, help protect the planet. 

And with the climate crisis in full swing, Earth might need all the clouds it can get.

Typically, cloud production calls for specific sulfur compounds released by seaborne plankton. The emission happens when hungry ocean animals take bites out of these creatures, breaking their cell walls. But according to research published Monday in the Proceedings of the National Academy of Sciences, that precious element hits a roadblock while working to make little clouds -- other clouds. 

"It turns out that this story of cloud formation was really incomplete," Tim Bertram, a professor of chemistry at the University of Wisconsin-Madison and senior author of the new report, said in a statement.

Refining knowledge of cloud formation, as Bertram's study aims to do, could help us better understand how changes in the ocean might impact the gigantic feathery formations above us. 

Clouds are crucial for Earth's atmosphere -- on top of painting the sky, they reflect excess sunlight and modulate how much rainfall we get. That's why down the line, research like this could be instrumental in mapping effects of climate change. 

Bertram's work traces back to the genesis of clouds.

Clouds are a lot like cotton candy, and not just due to their fluff. Like the airy treat needs a stick to wrap around, cloud particles require a strong anchor to build upon. That's because they have to go from evaporated water back to liquid -- the droplets must grasp onto something.

The wisps gliding around Earth accomplish the feat with... plankton breath. Definitely not how cotton candy is made.

After these ocean-based creatures release dimethyl sulfide, or DMS, which includes two carbon atoms and a sulfur atom, it turns into airborne sulfuric acid.

Sulfuric acid becomes a helpful tool for cloud particles to stick to until they grow into the whimsical puffs we admire in the cerulean sky. Essentially, blobs of the chemical are kind of like cloud nuclei.

"Over the last three or four years," Bertram said, "we've been questioning parts of that story, both through laboratory experiments and with large-scale field experiments. Now, we can better connect the dots between what's emitted from the ocean and how you form these particulates that encourage cloud formation."

Bertram refers to how a few years ago, a group of scientists came to a novel realization about clouds' origins. Before the plankton-produced DMS completely turns into sulfuric acid, it was found to reach an intermediate stage called hydroperoxymethyl thioformate, or HPMTF. At the time, HPMTF was a totally new concept.

To truly understand how HPMTF operates in the sky, Bertram and fellow researchers chartered a massive, NASA-owned DC-8  aircraft to check it out for themselves.

"It's a flying laboratory," he said. "Essentially, all of the seats have been removed, and very precise chemical instrumentation has been put in that allows the team to measure, at very low concentrations, both the emitted molecules in the atmosphere and all of the chemical intermediates."

Surprisingly, they calculated that upon reaching the intermediate step, about 36% of sulfur necessary for cloud formation is lost to clouds that already exist in the atmosphere. When other clouds weren't present in the vicinity of the sulfuric cloud seedlings, the team saw baby clouds birthed at a normal rate.

"This loss of sulfur to the clouds reduces the formation rate of small particles, so it reduces the formation rate of the cloud nuclei themselves," Bertram said. "The impact on cloud brightness and other properties will have to be explored in the future."