With reference to “Coriolis force”, which of the following statements is/are correct?

  1. It increases with increase in wind velocity.
  2. It is maximum at the poles and is absent at the equator.

Select the answer using the code given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer: (c) Both 1 and 2


  • Statement 1: It increases with increase in wind velocity.
    • The Coriolis force is directly proportional to the velocity of the moving object. As the wind speed increases, the deflection caused by the Coriolis force also increases. This means that higher wind speeds result in a greater Coriolis effect, leading to more significant deflection of the wind’s path.
  • Statement 2: It is maximum at the poles and is absent at the equator.
    • The Coriolis force is maximum at the poles and absent at the equator. This is because the Coriolis effect is directly proportional to the sine of the latitude. At the poles, the latitude is 90 degrees, making the sine value 1, thus maximizing the Coriolis force. At the equator, the latitude is 0 degrees, making the sine value 0, thus nullifying the Coriolis force.

Learn more

  • Definition: The Coriolis force is an inertial force that acts on objects in motion within a rotating frame of reference, such as the Earth. It causes moving objects to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
  • Cause: The primary cause of the Coriolis effect is the rotation of the Earth. As the Earth spins, different latitudes rotate at different speeds, causing the deflection of moving objects.
  • Impact on Weather: The Coriolis effect significantly influences weather patterns. It affects the direction of trade windscyclones, and ocean currents. In the Northern Hemisphere, cyclones rotate counterclockwise, while in the Southern Hemisphere, they rotate clockwise.
  • Dependence on Latitude: The Coriolis force is zero at the equator and increases with latitude, reaching its maximum at the poles. This variation is due to the change in the tangential velocity of the Earth’s surface with latitude.
  • Impact on Human Activities: The Coriolis effect impacts aviation and ballistics. Pilots and snipers must account for the Coriolis force when charting flight paths or aiming over long distances.
  • Examples: A common example is the deflection of a projectile fired northward from the equator, which lands east of its intended path due to the higher eastward velocity at the equator compared to higher latitudes.
  • Mathematical Expression: The magnitude of the Coriolis force is given by the formula 2𝜈𝜔sin⁡𝜙, where 𝜈 is the velocity of the object, 𝜔 is the angular velocity of the Earth, and ϕ is the latitude.
  • Global Wind Patterns: The Coriolis effect contributes to the formation of Hadley cellsFerrel cells, and Polar cells, which are responsible for the prevailing wind patterns observed on Earth.
Reflection in IAS EXPRESS

Geography Notes >> Pressure & Winds


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