Geostrophic Wind & Gradient Wind

Geostrophic Wind

and

Gradient Wind

Praveen Kumar SinghM. Sc. Environmental Science

Central University of Rajasthan

Geostrophic Wind

The Geostrophic Equation

Expresses the magnitude of the wind speed as a functionof the geopotential height gradient on a constant pressuresurface.

Where, go = gravitational acceleration,f = Coriolis parameter = 2Ωsin(Φ).Ω = angular velocity vector of the planet (7.292 x 10-5 s-

1 )f ranges from -1.4 x 10-4 s-1 at South Pole to +1.4 x 10-4

s-1 at the North Pole.f ≈ about 1 x 10-4 s-1 for mid-latitudes.

Zf

gv h

og

Elements of Geostrophic Balance

A. Pressure Gradient Force

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B.

Image coriolis force

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The Geostrophic Balance

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Geostrophic winds exist in locations where there are nofrictional forces and the isobars are straight. Isobars arealmost always curved and are very rarely evenlyspaced. This changes the geostrophic winds so thatthey are no longer geostrophic but are instead ingradient wind balance.

Gradient Wind

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Thank You…