geostrophic wind

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun meteorology A wind whose direction and speed are determined by a balance of the horizontal pressure gradient force and the force due to the earth's rotation to the left in the northern hemisphere and to the right in the southern hemisphere.
• noun meteorology That horizontal wind velocity for which the Coriolis force exactly balances the horizontal pressure gradient force. The geostrophic wind is thus directed along the contour lines on a constant-pressure surface (or along the isobars in a geopotential surface) with low elevations (or low pressure) to the left in the northern hemisphere and to the right in the southern hemisphere.