🌍 Why is Coriolis Force Zero at the Equator? UPSC Notes

Reason:Coriolis force depends on Earth's rotation and latitude. Its strength is proportional to sin(θ) where θ = latitude.At the equator (latitude=0).

What is Coriolis Force?

  • Coriolis force is an apparent force that acts on moving objects (like winds, ocean currents) when they are viewed from a rotating frame (Earth is rotating).

  • It deflects the path of moving objects:

    • To the right in the Northern Hemisphere.

    • To the left in the Southern Hemisphere.


🌍 Why is Coriolis Force Zero at the Equator?

👉 Reason:

  • Coriolis force depends on Earth's rotation and latitude.

  • Its strength is proportional to sin(θ) where θ = latitude.

  • At the equator (latitude = 0°):

    • sin(0°) = 0.

    • So, Coriolis force = 0.

In simple words:

  • At the equator, the effect of Earth's rotation on moving objects becomes negligible.

  • Thus, moving objects at the equator move straight without deflection.


🧠 Easy Example:

  • Suppose a rocket is launched exactly along the equator (say, from Kenya).

  • It will move straight, without any right or left deflection.

  • But if launched from Delhi or New York (far from the equator), it will slightly bend due to Coriolis force.


🔥 Quick Bullet Points for Revision:

  • Coriolis force = 2 × mass × velocity × angular velocity × sin(latitude).

  • sin(0°) = 0, hence Coriolis force is zero at equator.

  • No deflection of wind or ocean currents at the equator.

  • Important in trade winds, tropical cyclone formation (cyclones can't form exactly at equator!).

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