geostrophic wind

(redirected from Geostrophic balance)

geostrophic wind

[¦jē·ō¦sträf·ik ′wind]
(meteorology)
That horizontal wind velocity for which the Coriolis acceleration exactly balances the horizontal pressure force.

Geostrophic Wind

 

a horizontal, even, and straight movement of air with no force of friction and with balance in the gradient of pressure and the deflecting force of the earth’s rotation; the simplest theoretical scheme of air movement of the rotating earth. The actual wind in atmospheric layers higher than 1 km above the earth’s surface is close to the geostrophic wind. The geostrophic wind is directed along the isobar, with an area of low pressure remaining to the left of the stream in the northern hemisphere and to the right in the southern. The velocity of the geostrophic wind is proportional to the magnitude of the horizontal gradient of pressure. With equal gradients it is inversely proportional to the density of the air and the sine of geographic latitude and therefore increases with elevation and with increasing nearness to the equator.

geostrophic wind

geostrophic wind
Pressure-gradient force causes air parcel to accelerate. Coriolis begins deflecting air to the right. Coriolis increases as speed increases. Coriolis eventually balances pressure gradient forces.
That horizontal wind velocity for which the Coriolis acceleration exactly balances the horizontal pressure or gradient force.
References in periodicals archive ?
The pressure gradient force and Coriolis force soon find a balance with each other that we call geostrophic balance.
The slow component is in geostrophic balance and it is dependent only on the steric part of horizontal pressure, which is deduced from the temperature (T) and salinity (S) fields, which are the control variables of the system.
The model simulation conserved the convexity of the isotherms in other depths except at 30-40 m due to adjustments towards geostrophic balance (Fig.
Weaker zonal mean zonal winds are also observed at high latitudes in the winter hemisphere during strong El Nino events (not shown) accompanied by the warm anomalies, as expected from geostrophic balance.
Randall presents a graduate-level introductory overview of the global circulation of the atmosphere for students who have completed a graduate course in atmospheric dynamics and are familiar with such concepts as the equation of motion, the approximate hydrostatic and geostrophic balances, potential temperatures, vorticity, pressure coordinates, and planetary waves.