Definition of Geostrophic Flow

When the isobars are straight, parallel lines, and the only two forces acting on a parcel are the PGF and the CF, then the wind is called the geostrophic wind:

• PGF and CF are equal in strength (magnitude) and opposite in direction

• The geostrophic wind is always parallel to the isobars (height lines on an isobaric chart)

• let's look at the 500 mb chart....