New research from NASA indicates that photons move like ants, except photons are smaller and less crunchy. A team led by Yongxiang Hu of NASA’s Langley Research Center found a correlation between how long it takes for an ant to enter and exit a colony and how long it takes a photon to enter and exit snow. The team’s findings point toward a simpler method for measuring snow depth that, in turn, has bearings on studying climate, weather, and Earth’s water cycle. Hu borrowed a chapter from mathematics and biology research that observed that the average time an ant spends wandering around inside a colony before emerging corresponds to ~4× the volume of the colony divided by its surface area. Courtesy of iStock.com/atakan. Naturally, this led Hu to think about clouds, photons, and snow. “I studied properties of clouds and learned light bounces among cloud particles randomly, similar to the ants’ movement inside its colony,” he said. “So, I thought that the ants theory might apply to snow, too, since snow comes from clouds.” Hu and his team developed a model simulation to verify that the math translated from ant behavior to that of photons. They found that it was possible to use a similar equation to measure both. In the same way that an ant goes inside the colony and moves about randomly before coming back out, a photon of light from a lidar instrument enters snow and is scattered randomly within the snow particles before it exits. By applying the model simulation to lidar measurements taken by NASA’s ICESat-2 satellite, the researchers measured the average distance a photon traveled in snow. The simulation showed that snow depth was approximately half the average distance that the photon traveled inside the snow. The technique will enable future researchers to measure the depth of layers of snow covering sea ice surfaces and mountains to gain a clearer picture of how the climate crisis is affecting sea ice thickness, as well as the thickness of glaciers over land. Snowpack provides significant water resources in many regions of the world, making it important for water resource management. Compared to forecasting snowfall, forecasting rainfall is relatively easy. Climate models consistently predict an increase in global rainfall of anywhere between 3% and 7%. But estimating how snowfalls may decline in midlatitude regions as a result of global warming is much more complex. This is where Hu’s technique could make a difference. “I am confident this technique will revolutionize how we forecast snow evolution in the future and model sea ice changes, and we are already working on the design of the next generation of satellites specifically for snow depth,” he said. Who knew that spying on the personal habits of ants could produce insights about global precipitation?