In the future, weather forecasts and climate-change studies could become more accurate, thanks to new research on how clouds overlap conducted by a Cleveland State University faculty member and his colleagues.

Thijs Heus, Ph.D., of the CSU Department of Physics is a co-author of “Overlap Statistics of Shallow Boundary Layer Clouds: Comparing Ground-Based Observations with Large-Eddy Simulations,” published recently in the American Geophysical Union journal Geophysical Research Letters and featured as a Research Spotlight on Eos, a leading source for news about the Earth and space sciences.

“Clouds are the biggest unknown in the climate system,” said Dr. Heus, who came to CSU in 2014. He previously was a member of the Institute for Geophysics and Meteorology at the University of Cologne in Germany.

For their paper, Dr. Heus and four colleagues from the Institute for Geophysics and Meteorology – Dr. Gabriele Corbetta, Dr. Emiliano Orlandi, Dr. Roel Neggers and Dr. Susanne Crewell – studied the overlap of low-lying cumulus clouds.

The research team calculated the ratio between cloud volume and cloud area at different altitudes. The higher the ratio, the more the clouds overlapped. When clouds overlap, it affects the amount of heat that enters or escapes Earth’s atmosphere, which ultimately influences weather and climate.

In comparing cloud observations from the Juelich Observatory for Cloud Evolution in Germany with intricate computer models designed to replicate atmospheric turbulence, the scientists found a mathematical function that matched observed and simulated overlap patterns.

“We discovered that small clouds in particular have a lot less overlap than previously thought, based on research that focused more on larger clouds,” Dr. Heus said.

“Our research suggests that small clouds would generate a higher cloud cover – with more reflection of sunlight and a cooling effect from reflecting the sunlight – than previously predicted. This knowledge should increase the accuracy of weather and climate prediction.”