Location
MC 5501
Speaker
Dan Kirshbaum, McGill University
Title
The making (and modelling) of a thunderstorm
Abstract
Thunderstorms represent an essential component of midlatitude and tropical climates, providing rainfall for the survival of plants and animals. However, they also commonly lead to flash-flooding and other hydro-meteorological hazards (lightning, hail, and damaging winds) during the Canadian summer, and their uneven spatial coverage can lead to localized droughts. Moreover, their dynamics are extremely nonlinear and chaotic, making them difficult to understand and predict. These challenges render the study of thunderstorms an important unresolved problem with major implications for science and society. In this presentation, the dynamical behaviour of thunderstorms is covered from different perspectives. The basic thermodynamic and kinematic ingredients for these storms to develop are first reviewed, followed by exposition of the physical processes that complicate this picture and demand further research. The latter include, but are not limited to, cloud entrainment, detrainment, pressure perturbations, and environmental sensitivities. Next, the requirements and challenges for numerically simulating thunderstorms are described, including the importance of model grid spacing, advection, subgrid parameterizations, and ensemble forecasting. Finally, a (relatively) simple 1D model for thunderstorms is described and compared to the results of corresponding large-eddy simulations. Although the 1D model does not perfectly match the simulated results, it highlights the various interacting processes controlling thunderstorms and the areas in which the modern understanding remains incomplete.
This event is part of the NSERC CREATE-funded Quantitative Climate Science summer school. More information about this initiative can be found at https://qcs-create2024.github.io/
