# Pressure-gradient force

**Learn about this topic** in these articles:

### Buys Ballot’s law

- In Buys Ballot's law
…between the wind and the pressure gradient is a right angle. This is almost exactly true in the free atmosphere, but not near the surface. Near the ground, the angle is usually less than 90° because of friction between the air and the surface and the turning of the wind…

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### geostrophic motion

- In geostrophic motion
…the Earth’s rotation) and the pressure-gradient force. The velocity of the flow is proportional to the gradient of the pressure and inversely proportional to latitude. Although observed fluid motions are not strictly geostrophic, large-scale oceanic and atmospheric movements approach the ideal; that is, the geostrophic current usually represents the actual…

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### gradient winds

- In gradient wind
Around a low-pressure centre, the pressure-gradient force directed inward balances the Coriolis force and the centrifugal force, both directed outward; because the Coriolis force acts to the wind’s right in the Northern Hemisphere and to its left in the Southern, the wind blows counterclockwise along the curved isobars in the…

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### ocean currents

- In ocean current: Pressure gradients
The hydrostatic pressure,

Read More*p*, at any depth below the sea surface is given by the equation*p*=*gρz*, where*g*is the acceleration of gravity,*ρ*is the density of seawater, which increases with depth, and*z*is the depth below the…