Cyclones & Anticyclones

The swirling motions evident in the preceding animations are consequences of frontal systems anchored to high and low pressure systems, which are also called anticyclones and cyclones, respectively. The wind flow around high pressure (anticyclonic) systems is clockwise in the Northern hemisphere and counterclockwise in the Southern hemisphere. The corresponding flow around low pressure (cyclonic) systems is counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere. This is a consequence of the Coriolis force, as illustrated for the Northern hemisphere in the following figure.

Low pressure systems (left) and high pressure systems (right) in the Northern hemisphere