Question

what is pressure gradient force

Answer 1

The pressure-gradient force is the force which results when there is a difference in pressure across a surface. In general, a pressure is a force per unit area, across a surface

Answer 2

1. The pressure gradient force is the force which results when there is a difference in pressure across a surface.
2. Force is always directed from the region of higher-pressure to the region of lower-pressure.
3. The pressure gradient force is balanced by the gravitational force, maintaining hydrostatic equilibrium.
4. In the Earth's atmosphere,  air pressure decreases at increasing altitudes above the Earth's surface, thus providing a pressure gradient force which counteracts the force of gravity on the atmosphere.