In the year of 1918, the last years of the World War 1, the German military pointed its last and largest artillery with a slight turn to the right. There were numerous reasons to why they had slightly changed the very trajectory of the artillery. Perhaps due to the curve of the Earth, the rotation, or many other things. But a key factor behind this slight turn is the Coriolis effect (Collins). The reason behind weather patterns, ocean currents, and many other wonders of mother nature can be explained by a single ideology: the Coriolis Effect. The origins of the Coriolis effects can be traced back to the 1800s when, French scientist and mathematician, Gaspard-Gustav Coriolis was deriving the math behind rotating devices such as waterwheels as this was the peak of the industrial revolution. Coriolis also worked rotating hydraulic machinery, trying to formulate the principles surrounding physics at that time (Gaspard). The initial stages of this new discovery were published in a paper titled “Sur les equations du movement relative des systems de corps”, which translates to “On the equations of Relative Movement of Systems of bodies” (Gaspard). This effect basically summarizes the observations of the behavior of bodies in a rotating frame or reference. He established a fundamental concept of engineering mathematics, work, and kinetic energy. This theory is based off 3 main physics principles: Newton’s 1st (objects in motion tend to stay in motion), spherical geometry of the earth (latitudes & longitudes), and centripetal acceleration (Van Domelen).
Imagine a rotating disk with Point A and Point B as shown in the image to the right. Assume that point A is halfway through the distance from center to point B. When both points begin to spin, both will complete a period at the same time. But point B would have covered a longer distance when compared to point A. Given that, we also know that when two things cover a certain distance at the same time, the one that covers the higher amount of distance is the one that moves faster (Siegel). In other words, the curve that is observed when a ball is pushed from a merry-go-round is not because of the push but because of the rotation of the merry-go-round. But the actual question is how does this connect to the real world? Although this effect can be observed in almost all of the objects, it is the most noticeable on large-scale atmospheric phenomenon such as ocean currents and hurricane patterns. When this rotating disk is replaced with the Earth, the same principles apply. Points closer to the equator of the Earth would travel faster than the points that are closer to the North or South Pole (United). To be exact, the equatorial regions travel at 1600 kilometer per hour, while regions close to the poles travel at a speed of 0.00008 kilometer per hour (Rahul). And when the merry-go-round is replaced with the Earth, the Earth created a reference frame, and the objects move around the reference frame. In general, in relations to this theory, the earth is always considered the rotating reference. In simple terms, the moving coordinate system has rotation (Wang). This ideology can be explained with the Earth’s rotation, and the different latitudes.
The mathematical definition of this very concept is as follows.
Where is the Coriolis force, m is the mass of the rotating object, is the tangential velocity, and the is the angular velocity.
When this spherical shape is transformed into a flat map, it betters helps explain the basic principle of how hurricanes and oceans currents work. As mentioned earlier, clouds, or anything, near the equator seems to move faster than clouds near the North or the South pole (McDonald). When these clouds become low pressure points, as a gush of wind pushes it towards the North pole, they tend to fall behind the rest of the clouds. When they fall a little behind in the reference frame, it creates the hurricane effect. Due to this Coriolis effect, hurricanes near the North pole tend to move in the counterclockwise direction, or in general, objects in the Northern hemisphere deflection to the right. While the hurricanes near the South pole tend to spin in in clockwise direction, or in general, objects in the southern hemisphere tend to deflect to the left.
A similar theory is applied to the ocean currents that take place in all of Earth’s Ocean. Since now the reference frame has changed, the ocean currents in the Northern hemisphere tend to move in the clockwise direction, while the currents in the Southern hemisphere tend to move in the counterclockwise direction due to this Coriolis effect (Refer to image 1.4). It is also important to note that both the ocean currents and hurricane patterns do not solely depend on the Coriolis effect (Alexander). There are various other factors such as topography, pressure, and many others, that greatly influence these patterns as well. Another meteorological example of this object is when fast-moving currents of air form jet streams. The Coriolis effect deflects these current as well, which in turn influences other weather patterns. Similarly, other than profound effects on the weather, the Coriolis effect has an impact Ballistic missiles and long-range projectiles. If a cannon is fired northward from the equator, it would seem as if it were being deflected to the east of its original direction (“Coriolis”). The Coriolis effect also plays a huge role in modern day rocket studies, and aerodynamics. A pilot must consider of this force in order to minimize the deflection that occurs during the travel. Even military snipers consider the effects of this force in their work (Rahul). Even though the bullets that are fired do not have much of an impact due to this force, but the precision required for this job demands consideration of the Coriolis effect.
In conclusion, the Coriolis effect, a fictious rotational force, is a very important concept that governs the key movements of large-scale weather patterns and ocean currents on our Earth.