Chapter 11

Geostrophic Wind and Gradient Wind

Praveen Kumar SinghM. Sc. Environmental ScienceCentral University of Rajasthan

Geostrophic Wind

The Geostrophic Equation

Expresses the magnitude of the wind speed as a function of the geopotential height gradient on a constant pressure surface.

Where, go = gravitational acceleration, f = Coriolis parameter = 2sin(). = 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.

Elements of Geostrophic Balance A. Pressure Gradient Force

Continued..Continued..

B.

Image coriolis forceContinued..

Continued..The Geostrophic Balance

Continued..

Geostrophic winds exist in locations where there are no frictional forces and the isobars are straight. Isobars are almost always curved and are very rarely evenly spaced. This changes the geostrophic winds so that they are no longer geostrophic but are instead in gradient wind balance. Gradient Wind

Continued..

Continued..

Continued..

Thank You