Balanced Flow - Geostrophic Flow

Geostrophic Flow

An easterly westerly stream flow of global scale spans, approximately along parallels, from Russia over Europe as fas as the mid latitude Atlantic Ocean An northerly air stream flows from Arctic to mid latitudes south of the 40th parallel A northwesterly stream sets in between two large-scale counter-rotating curved flows (cyclone and anticyclone ). Close isobars indicate high speeds © British Crown Copyright 2008, 2009 and 2010, The Met Office

Geostrophic flow describes a steady-state flow in a spatially varying pressure field when

• frictional effects are neglected; and:
• the entire pressure gradient exactly balances the Coriolis force alone (resulting in no curvature).

The name 'geostrophic' stems from the Greek words 'ge' (Earth) and 'strephein' (to turn). This etymology does not suggest turning of trajectories, rather a rotation around the Earth.