By Kathleen Berger, Executive Producer for Science and Technology

December brings to mind things like “dreaming of a white Christmas” or thoughts of just “letting it snow,” along with all the fun that goes along with it. It’s kind of like that in the AIR Lab at Washington University in St. Louis.

“You can see it has that soft, powdery texture that you see in freshly fallen snow,” said Ganesh Chelluboyina, a 5th-year PhD candidate at WashU.

Chelluboyina created a four-foot-tall chamber that’s referred to as a snow globe.

“It’s three Styrofoam boxes stacked on top of each other,” he said.

Regardless of its shape and material, it’s called a snow globe because of what’s happening inside—much like traditional snow globes, only the lab’s version is based on science.

“We introduce liquid nitrogen through the bottom. We’re pushing water at a very high pressure. These water droplets are less than 100 nanometers, and they get flash frozen, very similar to snow in the real world,” Chelluboyina explained.

He’s setting the stage to determine what actually happens after wildfires, when dark brown carbon particles deposit on snow. His concern is global warming, specifically with accelerated snowmelt from wildfires.

“When wildfires produce huge plumes of smoke, some of the smoke eventually lands on glaciers, darkening their surface and causing them to trap more solar radiation. This can enhance their melting rate and cause glacier recession,” Chelluboyina said.

The AIR Lab, or the Aerosol Interdisciplinary Research Group Lab, first discovered that dark brown carbon is a hidden source of accelerated snowmelt in midlatitude glaciers.

“This particle was not previously considered to be an important light absorber,” he said.

Previous research, which involved members of the AIR Lab chasing wildfires and sampling the air, led to new insights and additional research.

“This field campaign was the first to identify, characterize, and show that dark brown carbon is at least four to 10 times more abundant than the well-understood particle, which is black carbon,” he said. “Now, in the modeling study I published, when we include both dark brown carbon and black carbon, we see that this warming enhancement is up to two times greater compared to just black carbon, which was the previously well-understood carbon in snow. My research takes it a step further, in terms of what happens if this smoke deposits on snow.”

The goal of the lab’s snow globe is to manufacture snow for the deposition of particles that essentially mimic wildfire aerosols.

“He’s trying to validate an agent that gives rise to enhanced snowmelt and see if his model calculations can be observed in a laboratory setting,” said Rajan Chakrabarty, PhD, AIR Lab’s principal investigator.

Chelluboyina’s research could go a long way in ensuring accurate climate models and measurements.