Résumé : There is an increasing interest for the application of Computational Fluid Dynamics (CFD) to the study of flows in the lower part of the atmospheric boundary layer (ABL). The simulation of atmospheric flows, often over complex domain, is necessary for the estimation of wind loads on buildings, wind turbine siting, pollutant dispersion and pedestrian wind comfort.The present online Lecture Series offers a wide overview of the state-of-the-art, with applications ranging from microclimate, wind engineering, to mesoscale, meteorology, and their coupling. Reynolds Averaging (RANS) and Large-Eddy (LES) approaches are discussed and their respective capabilities at meso- and microscales are evaluated, with focus on realistic inflow, wall modelling, Uncertainty Quantification and validation. The discussion is completed by the presentation of examples of practical implementation for Open Source Codes such as WRF and OpenFOAM as well as in-house and commercial CFD software.The lecture series directors are Prof. Jeroen van Beeck and Dr. Sophia Buckingham from the von Karman Institute.