Coriolis Force (Basics of Geography) – UPSC Notes/PDF

People often make mistakes by not understanding the basics. They start reading and understanding important phenomena like cyclones, tornados, etc. But you will remember those concepts only for a short duration if you don’t know the basics associated with it. So, please try to give more time to the basics. But people find it difficult to understand basics and consider it as a complex. Here, I have made it simple for you in an amazing way.

Before reading this, I assume that you have read about the Pressure System. There I have explained the concept of High Pressure and Low Pressure. Here we will try to understand, how many types of winds we have and the question which arose in the ‘Pressure System’. Why winds between two latitudes move in a curvy nature.

The main concept, that you have to learn is ‘Coriolis Force’. It is an interesting topic, it is relevant to understand Cyclone formation. So let’s get started.

Coriolis Force

Definition: It is a force generated due to rotation of the earth.

What the hell was that? What force?

Don’t panic, let’s understand by an example.

  • In the above picture, we have our earth and two persons on the lines AB and CD. Suppose, you are on the line AB and I am on the line CD.
  • We both are just standing at a fixed point. You are just in front of me. And the earth is rotating. The earth completes its one round/rotation. But still, we are in the same position. You are still in front of me even though your path is shorter than mine.
  • Who is faster? I am. Because your path is shorter than mine. In other words, my speed is more than you.
  • Now, if you throw a ball towards me while the earth is rotating. The ball will not reach/hit me rather it will go behind me. (because I am faster than you) Isn’t is true.
  • And, if I throw a ball at you, the ball will be ahead of you. Because the ball also got the momentum (2nd law of motion)

There are two observations from the above example:

(i) if something comes from slow to fast, it will go behind.

(ii) if something comes from fast to slow, it will go ahead.

Another thing to observe is that:

(i) The ball will move in a clockwise direction in the northern hemisphere.

(ii) The ball will move in anti-clockwise direction in the southern hemisphere (Do it yourself).

This is the Coriolis Force. Remember the definition, ‘the force generated due to the rotation of the earth’. And the above two points are the implication/result of the rotation of the earth i.e. Coriolis force.

The winds move from High Pressure to Low Pressure.

  • At 30°, we have high pressure and at 0° we have low pressure. So, the air moves from 30° latitude to 0° latitude.
  • Again at 60° latitude, we have low pressure and at 30° latitude, we have high pressure. Therefore, winds move from 30° latitude to 60° latitude.
  • At 90°, we have high pressure and at 60° we have low pressure. Hence, winds move from 90° latitude to 60° latitude.

Why do winds move from high pressure to low pressure in curvy nature? Let us understand it in latitudinal wise. But before that, you must know that earth rotates from east to west. That is why we experience morning in Japan first than India or we experience morning in Arunachal Pradesh first than Gujarat.

Source: ResearchGate

Between 0° to 30° North/South

  • 0° latitude is comparatively faster than 30° latitude. The winds will move from 30° latitude (high pressure) to 0° latitude (low pressure) and will go behind.

Between 30° to 60° North/South

  • 30° latitude is comparatively faster than 60° latitude. The winds will move from 30° latitude (high pressure) to 60° latitude (low pressure) and will go ahead.

Between 60° to 90° North/South

  • 60° latitude is comparatively faster than 90° latitude. The winds will move from 90° latitude (high pressure) to 60° latitude (low pressure) and will go behind.

Related Post

Pressure System (Basics of Geography)