This lecture explores the impact of mountains on atmospheric flow, local weather, and climate. Topics covered include stability of the atmosphere, thermally driven circulation, flow interaction with topography, orographic precipitation, downslope winds, and frontal passage. The lecture delves into concepts such as Brunt-Väisälä frequency, flow interactions with topography, orographic precipitation mechanisms, downslope winds like Föhn and Bora, mountain waves, and local winds like Joran.