An Etymological Dictionary of Astronomy and Astrophysics

Meteo.: A wind which is balanced by the → Coriolis effect and → pressure gradient force.

An air parcel initially at rest will move from high pressure
to low pressure because of the pressure gradient force. 
However, the air parcel in its movement is
deflected by the Coriolis force, to the right in the northern 
hemisphere and to the left on the southern hemisphere. As the
wind gains speed, the deflection increases until the Coriolis
force equals the pressure gradient force. At this point, the
wind will be blowing parallel to the → <i><a class="linkVoir" href="/terms/isobar/">isobar</a></i>s.

See also: → geostrophic; → wind.