The Coriolis force and wind patterns

Graphic - winds
The Coriolis Effect can cause cyclic wind patterns on Earth. Source
The earth’s rotation about its axis means that it is not perfectly inertial. Though generally small, the associated effects do have a significant impact on large-scale motion across the earth’s surface– in particular on wind patterns. As air is driven down a pressure gradient it is deflected by the Coriolis force to form circular paths centred on the high-pressure region. The paths have a different sense in the northern and southern hemispheres (clockwise above the equator, anticlockwise below). A similar effect is supposed to be evident in the path followed by the water in your bath, as it drains away (remember this picture?). But this is rather doubtful, as you will find on this debunking page.