What Is the Coriolis Effect?

If you happen to live in the Northern Hemisphere, have you ever wondered why the water swirls counter-clockwise in your toilet bowl? Or, whenever there is a hurricane and or a tornado, the winds are swirling counter-clockwise as well? Here’s another typical example: The drainage of water in your bathtub does the same.

All things being equal, the vice-versa could happen in the southern hemisphere. This behavior is called the “Coriolis Effect.” Technically, it may not always affect such small water bodies, as the scale of the force might be too weak, but they are good common visual examples to understand what the phenomenon is.

Can You Explain This in Simpler Terms?

Here’s another image for you. It’s not exactly a 1:1 match, but I am confident it will give you an idea. Assume that you’re (you being northern hemisphere) racing a 100 meters sprint. The person on the right side to you (being the equator), is actually faster than you. Just as they’re about to overtake you, you look to your right.

NOW, because that person is faster than you, he or she will not be at the same point as he or she was before. And at the moment (however small), your eyesight will end up to the right of that person because of their speed. They ended up ahead!

Similar to this visualization, that’s pretty much what the Coriolis effect is. It’s basically this occurrence of the deflection of objects from an originally intended straight path. Read on, you’ll get a more thorough understanding!

Why Does the Coriolis Effect Happen?

Typically, this effect is felt more viably on large scales. Think Airplanes, and weather conditions. The primary reason for this is because the earth rotates at different speeds in different places (faster towards the center/equator, slower towards the ends [poles]). In other words, the speed of the rotation is felt more at the equator, versus that at a pole. Say, for instance, you throw a ball from the northern hemisphere to the equator (think the 100 meters sprint example). When all is said and done, the ball will land towards the right of the intended target, simply because the equator rotates faster than you. See the screenshot below reference. (Original source of the image: effect from northern hemisphere to equator

In What Situations Does the Concept of Coriolis Effect Help?

Because we now know what this phenomenon is, actual calculations to accommodate for this effect are taken into account. For example, Snipers sometimes have to take this into consideration, as even a slight deflection can end up missing the target. Even pilots, have to be prepared for this — especially over large distances. Planes simply cannot afford to travel in straight lines; otherwise, they might end up towards the left or right of the final destination. Think, why do flight paths always appear curved, and not a straight line? Another common example of this would be for weather predictions, studying wind patterns, etc.

Why Is There No Coriolis Effect at the Equator?

Technically speaking, it’s not that there is no effect, the effect becomes zero. Without getting super nerdy and discussing equations (which honestly, I cannot grasp), based on my understanding, I believe the reason for the most minimal effect at the equator is because you’re already at the maximum speed possible. Another way to think about it is that there is no difference in the speed; because it’s always the same, there is no deflection.

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