Humans have grown to appreciate predictability—you could say we come by it naturally on a planet where the sun rises and sets according to a reliable pattern and seasons change in rhythm. But as we dig deeper into the complexity of nature, predictability becomes elusive, particularly when it comes to weather.

Thankfully, meteorologists have come a long way in understanding, inventing instruments and developing capabilities to forecast climate patterns and storms, saving countless lives in the process. 

Despite advancements, there is one facet of weather that remains mired in mystery: clouds. But two University of Oklahoma College of Atmospheric and Geographic Sciences researchers—Greg McFarquhar and Scott Salesky—are among a small cadre of scientists who have taken up the bold challenge of untangling this chaotic web, each in their own way.

McFarquhar has been studying clouds since 1987 and is among the world’s top scientists in the field of cloud physics. 

“Clouds are very complex,” says the director of OU’s Cooperative Institute for Severe and High-Impact Weather Research. “The fundamental uncertainty that exists in both weather and climate prediction today is our poor understanding of the basic properties of clouds and the processes occurring within them.”

McFarquhar was recently awarded a $600,000 grant from the U.S. Department of Defense. Meanwhile, Salesky, an associate professor in OU’s School of Meteorology, is part of OU’s Atmospheric Turbulence Group and received a nearly $470,000 DOD grant to fund cloud research in marine environments.

The DOD funding will help support both scientists’ individual efforts to understand the basic properties and processes within clouds and lay another brick in a growing foundation of knowledge that could someday lead to breakthroughs revolutionizing weather forecasting. Increased knowledge about cloud structure will also help the DOD improve the acuity of radar systems aboard U.S. ships and planes. 

Salesky’s goal is understanding how heat, humidity, turbulence and suspended particles can dictate cloud structure. By using simulations that replicate turbulence, Salesky’s team can test how different environmental conditions often shape the marine atmospheric boundary layer, or MABL. MABL fluctuations have significant impacts on weather and climate, he says. 

In fact, the number of potential environmental combinations are so vast that they could completely overwhelm existing computational power. Instead, Salesky’s team is forming a foundational model for others to follow.

“People have studied bits and pieces of this, but we’re trying to be systematic about it,” he says. “This is a very complicated problem and a building block in a growing body of cloud research.”

The complexity of McFarquhar’s own research is reflected in a common question he poses.

“I like to ask new students, ‘What’s the speed of light?’ ” McFarquhar says. “And they’ll immediately tell me the value. Then I’ll ask them to go look at a cloud out on the horizon and tell me how many cloud droplets are within a centimeter cubed in that cloud. They can’t give an answer because there is so much unknown.” 

To address the unknown, McFarquhar and other cloud researchers use models that employ data gathered with optical-array probes attached to airplane wings. The probes are flown through clouds to measure individual water droplets and ice crystals, characterizing them by shape, size and whether they are liquid or ice. The probes help determine the total number of ice crystals and water droplets in clouds, their sizes and how many grams of water there are per cubic meter.

McFarquhar says he’s been involved with 37 such field studies, and there are 14 other groups around the world conducting similar, data-gathering flights. In all, 300 datasets have been gathered by scientists worldwide. 

However, broad variability between these teams’ measurements is problematic, he says. Researchers are using different probes, airplanes and probe-processing algorithms. This confounds attempts to compare one dataset to another and complicates studying how cloud properties vary with environmental conditions.

McFarquhar is doing his part to fix this issue by creating an OU-based, open library of international project results and a system to help cloud researchers compare data sets. No one in the world has yet attempted such a comprehensive undertaking. But McFarquhar says his project is only a start. 

“Am I ever going to totally solve the variability problem? No, probably not,” he admits. “But there are a lot of things we can do to make real progress in understanding how clouds work. That’s what we have to concentrate on.” 

McFarquhar compares cloud physics to working on a 1,000-piece puzzle that only came with 21 pieces in the box.  

 “Our job is to take those puzzle pieces and try to figure out what’s going on,” he says. “Twenty-one pieces can give you a lot of good information; you have to concentrate on what you have and not on the 979 pieces that are missing.” 

Chip Minty is a Norman-based writer and the principal of Minty Communications, LLC.

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