Colloquium Series

Dr. David Muraki (Simon Fraser University)

Fluid Dynamics, Weather, and the Shape of Clouds

As residents of coastal BC, we have ample opportunity to observe cloud cover in the daily weather pattern. Much meteorological research has been directed to unstable and precipitating cloud types that are associated with storm activity. But less is known about the evolution of the mid-level, stable cloud cover that characterizes our gray winter days, a sunless fate often shared by about a quarter of the Earth's surface. Cloud layers are ephemeral, constantly appearing, reappearing and displaying a variety of shapes and patterns. Yet very little is understood about the fluid dynamics behind this evolving pattern in the sky.

This talk will present the fluid dynamics behind the partial differential equations that are central to our weather forecasting technology. The science of clouds also requires the inclusion of the thermodynamics of water. Tools from mathematical pattern formation have been adapted to track the location of the onset boundary of the vapour/liquid phase change and give an analytical model for the moving edges of clouds. Despite the approximations in the theory, several cloud patterns are confirmed by numerical simulation in a forecast weather model.