Why Coriolis force is maximum at Pole?

The Coriolis force is directly proportional to the angle of latitude. As the latitude at which horizontally and freely moving objects are located increases, the twisting of the underlying Earth’s surface due to the planet’s rotation increases. That is the Coriolis effect increases as the latitude increases. It is maximum at the poles and is absent at the equator.

Further Reading:

• Forces Affecting Velocity And Direction Of Wind
• Types of Wind