RUI: Toward a Comprehensive Theory of Mesoscopic Morphology of Ice

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This award from the Environmental Chemical Sciences and Physical and Dynamic Meteorology Programs of NSF supports Professor Steven Neshyba and his students at the University of Puget Sound. They study the surface texture ("roughness") of ice crystals in clouds. These ice particles play a significant role in Earth's weather. They influence how the clouds reflect and transmit sunlight. The mechanism by which such roughness develops is not well understood. This project includes experiments and computation. It aims to develop a theoretical description of the ice surface properties. Undergraduate students participate in the work as researchers, co-authors of papers and presentations, and collaborators. Other educational impacts include providing high school students and teachers from Lincoln High School hands-on experiences operating a scanning electron microscope. All of the researchers write computer codes to interpret the resulting images. Professor Neshyba travels with his students to collaborator laboratories in the Czech Republic and Norway helping them to gain an appreciation for science in an international context. In the laboratory, roughness properties of cirrus-like ice crystals are obtained by growing the crystals inside a variable-pressure scanning electron microscope. Molecular dynamics simulations explore the evolution of ice surface characteristics over complete cycles of ice layer growth. A coarse-grained model for ice growth extends the reach of these molecular-scale simulations to much larger time- and distance scales. These results are used to predict interactions with visible light, especially as pertinent to atmospheric remote sensing experiments. A predictive theory of ice crystal surface morphology can be achieved by integrating elements of ice growth dynamics across multiple scales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.