Pressure gradient force
Topic: Atmospheric Pressure, Winds and General Circulation · NCERT: Class 11, Ch 9 "Atmospheric Circulation and Weather Systems"
Meaning
The pressure gradient is how fast pressure changes over a distance. The pressure gradient force is the push this creates. It moves air from high pressure towards low pressure. It acts at right angles to the isobars, which are lines joining places of equal pressure. When the isobars are close together, pressure changes sharply, the force is strong and the winds are strong. When the isobars are far apart, the winds are light. This force starts every wind.
Example
A tropical cyclone over the Bay of Bengal shows tightly packed isobars around its centre. The steep pressure gradient there produces the very strong winds that hit the coasts of Odisha and Andhra Pradesh.
Don't confuse with
- Coriolis force: this does not start the wind. It only bends moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.