Q. With reference to "Coriolis force", which of the following statements is/are correct?
- It increases with increase in wind velocity.
- It is maximum at the poles and is absent at the equator.
Select the answer using the code given below: (UPSC Prelims 2024)
Answer:
Both 1 and 2
Notes: The correct answer is [C] Both 1 and 2.The Coriolis force is an apparent force caused by the Earth's rotation that deflects moving objects (like wind) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
Statement 1 – Correct:The Coriolis force is directly proportional to the velocity of the wind. The mathematical expression for the Coriolis acceleration is:
2 × v × ω × sin(φ),where
v is the wind velocity. As the speed of the wind increases, the magnitude of the deflection (Coriolis force) also increases.
Statement 2 – Correct:The Coriolis force is proportional to the sine of the latitude (
sin(φ)).
- At the Equator: The latitude φ is 0°, and sin(0°) = 0. Therefore, the Coriolis force is absent at the equator, which is why tropical cyclones do not form there.
- At the Poles: The latitude φ is 90°, and sin(90°) = 1 (maximum value). Thus, the Coriolis force is at its maximum at the poles.
The force always acts perpendicular to the direction of motion, meaning it changes the direction of the wind but not its speed. It plays a critical role in global atmospheric circulation and the formation of pressure systems.