One ASU professor is studying the effects rain splashes on decidedly dry environments.
Mark Schmeeckle, assistant professor of geography, is part of a team of researchers that has discovered the truth behind the patterns of rain splashes and their role in soil erosion.
Their findings are in the current issue of the Journal of Geophysical Research.
"One of the important factors that shapes the landscapes over time is rain splash, the splashing of particles by raindrops," Schmeeckle said.
While scientists have looked at the effects of rain showers on the environment, few have focused in on the power of single raindrops, Schmeeckle said.
"Very little work had been done at a fundamental level," he said. "Work had been done like raining on small plots of land and looking at what comes out, but not looking at the actual process of
individual raindrops and how they get splashed on [inclines]."
The team used a high-speed camera that takes 500 frames per second to focus in on the single rain splashes.
"How I was taught when I was in school is that if you have a splash that hits a slope, what would happen is you would get splash in all directions," Schmeeckle said. "But because some of the particles are traveling down slope, they are going to travel further than the ones that travel upslope."
Through his research, Schmeeckle found that this claim is not entirely true.
His team focused on raindrops falling on inclines that varied between zero and 30 degrees. They discovered that in reality, more particles are initially
thrown downslope than upslope.
"As it turns out when you look at the images, many more particles are thrown down slope initially, and they are thrown further, so their initial velocity is a lot greater downslope," Schmeeckle said.
Schmeeckle said that rain splashes are a big contributor to soil erosion in agricultural areas.
"If the soil is on a slope, each raindrop is going to cause that soil to splash around," Schmeeckle said. "Soil can be cohesive, and the rain splash will break apart the soil surface."
Soil erosion could be compared to a college student waking up for class, said geography professor Ronald Dorn, who is not involved with the study.
"The dirt on slopes would be like [a] student sleeping in," Dorn said. "The first step is getting the student out of bed. The raindrops would be like a buddy yanking you out."
Like Schmeeckle, Dorn is interested in geomorphology, the study of landscapes, and he said that he appreciates Schmeeckle's work to capture freeze-frame shots of the rain splashes.
"To me, that's really art," he said.
Reach the reporter at: stephanie.naufel@asu.edu.
