The mechanism of action of extratropical and intertropical atmospheric systems in Rio Grande do Sul, Brazil, during winter, reflects the polar air supply conditions in the subantarctic latitudes, the balance of forces between the centers of action, the efficiency of frontogenes and the trajectories of the polar fronts. From these dynamic factors, there are combinations of types that can be grouped into three succession models typical of the south-Rio-Grandense winter, obtained through the technique of rhythmic analysis and the interpretation of synoptic charts and meteorological satellite images.
