What is gradient force?

When a horizontal pressure gradient exists, a force, termed the pressure gradient force, acts on the air which make the air to move from high to low pressure at right angles to the isobars as shown below.15

However, for a number of reasons i.e. coriolis force or friction, the actual air motion observed at the surface is seldom in the direction of, or at the speed related to, this force.

ANKIT KUMAR SINGH