Definition:  It’s a phenomenon that causes fluids like H2O and air to curve as they travel across or above earth’s surface.

Basic concept to understand :

Before getting into it let’s talk about a small concept. Let’s imagine that you are in a huge turn-table turning in counter clockwise. As shown say you are green oval having a red ball with you and centre in blue.


As table is turning you and ball travel along tangent. Then you throw the ball towards the centre and so there are two velocities for ball. One’s radial velocity that’s in the direction of the radius towards the centre. 2nd one is the tangential velocity that was due to the rotation of the turn-table. As the ball have 2 perpendicular velocities the resultant velocity would be a diagonal vector. 

But to you the path will be different as you are on the turn-table your reference frame is itself rotating. So instead of going straight diagonally it will look like a curve as shown.

And you can understand this in some other way. we know that the point on the edge of the table will turn faster than the point near the centre because the former have to travel a long distance comparatively to latter in same time. In the diagram you can see 3 blue lines showing the magnitude of the speed of the points near the centre, mid-way, edge respectively. 

When you throw the ball towards the centre it will trace curve because considering a point just before the point on midway will have high turning speed than the later so ball will move right. Taking every point into consideration and adding them we will get a curved path.

If the turn-table is turning clockwise from your prospective then the ball will appear to curve left as shown.



The coriolis effect is often brought up in discussion of wheatear systems like hurricanes, cyclones, willy willy which indicates same strong low pressure systems on the earth. In the diagram you can have the side view of Earth having and poles.”L” indicates the low pressure system and two blue points indicates mass or volume of air to the North and south of L. 

We know that all points along the equator are on the earth radius as earth is a sphere axis passing through the centre of it. Where as points on poles almost lies on the axis of rotation whose speed would be very very low. Calling out our previous knowledge we can say points on equator spins faster than poles. We know that earth rotates from West to East i,e points on equator are moving towards the East the fastest. Mid latitude points moving east at medium speed and up in the poles quite slow.

Now take a close look at “L”. We know that air always travel from high pressure area to low pressure area i,e the Blue dots try to move towards the “L”. Talking about the volume of air on south side it will have high speed than the L since nearer to equator so it will trace a curve path to East of L. Now talking about the volume of air on North side it will have less speed than the that of L so it will trace a curve path to West of L w.r.t the prospective of a person on the ground.


So now we are left with a low pressure system swirls in a counter clockwise direction. 

And in the same way in the southern hemisphere pressure system swirls in clockwise direction.


We can also witness the coriolis effect during the Sniper shot. What happens is when the Sniper aims the target to the east or when he was about to take a target to East it will hit above the target.When he shoot west it will hit below the target.

For better understanding you can watch this video