Definition

Ignoring friction or depth changes; if a parcel of water with no initial relative vorticity (i.e. no rotation) is moved northward, as f (the Corio­lis parameter) increases the parcel will gain negative relative vorticity and will circulate clock­wise. The Coriolis force will be greater on the pole­ward side of the parcel than on the equatorward side and hence the parcel will be subjected to a net south­ward restoring force. This force will push the parcel south of the latitude of zero relative vorticity overshoots and the circulation becomes counterclockwi­se. Due to the Corio­lis variation the parcel will now experience a north­ward restoring force. Thus the variation of f provides a restoring force (in the horizontal plane) allowing oscillation to occur just as the effect of gravity does (vertically) for surface or internal waves. In reality Rossby waves are compli­cated by depth variations and frictional effects.