Question

Briefly explain which physical forces (pressure gradient, Coriolis, friction) you expect to dominate the dynamics of the following processes. Which of these processes are dominated by the geostrophic balance: Coriolis force ≈≈ pressure gradient.

(i) Surface waves

(ii) Internal waves

(iii) Tsunami

(iv) Mesoscale eddies

(v) Tides

(vi) Wind-driven circulation

(vii) Thermohaline circulation

Answer 1

Which physical forces that we expect to dominate the dynamics of the following processes.

Pressure gradient force & Coriolis force

Explanation : An air parcel initially at rest will move from high pressure to low pressure because of the "pressure gradient force" (PGF). However, as that air parcel begins to move, it is deflected by the "Coriolis force" (CF) to the right in a northern hemisphere (to the left on a southern hemisphere).

Which of these processes are dominated by the geostrophic balance?

Wind driven circulation

Option (vi) : it will be correct.

Explanation : Geostrophic wind which blows parallel to the isobars because Coriolis force and pressure gradient force are in balance. As the wind gains speed, the deflection increases until the Coriolis force equals the pressure gradient force.