Understanding the Coriolis Effect

My first encounter with the term Coriolis Effect was when I was playing Modern Warfare. During a section of the game, a sniper was advised by his spotter to consider Coriolis Effect when taking a shot to have a more accurate effect. So what really is Coriolis Effect?

Definition

Essentially, Coriolis Effect is the apparent curvature of ocean currents and winds, or anything that moves on or along the earth's surface. This effect is caused by the Earth's rotation. This dynamics is often overlooked and misunderstood although it is a very important factor in tackling physics and geometry issues. The easiest way to explain this phenomenon is the tendency of any moving object travelling on or above earth's surface to stray sideways from its normal course. Depending on your location, the deflection is towards the right in the northern hemisphere while the effect is towards the left in southern hemisphere. This phenomenon was first observed by a French engineer, Gaspar Coriolis. He eventually came up with mathematical formulas to explain it.

It must be noted that the surface of the earth does not rotate at the poles while rotation speed is at its maximum along the equator. This is the simplest explanation why objects moving further from the equator tend to drift towards the east while objects moving closer to the equator drift to the west. Artillery, bullets, winds, water flow, and virtually everything are subject to this effect.

Impacts of Coriolis Effect

This effect impacts the planet in many ways. The most crucial impact of this effect is on the ocean currents and wind directions. Obviously, man-made objects such as planes, missiles, bullets, are affected by this phenomenon. The most apparent manifestation of this effect is on wind movements and patterns. The speed of rising air from the surface of the earth is higher than the one in lower altitude. This is due to the fact that air on higher altitudes does not encounter the same level of drag affecting air on lower altitudes. Thus, a faster moving object has a greater Coriolis Effect, and the same is true for winds.

Although wind traveling over the surface of oceans can influence ocean currents, the Coriolis Effect has also a more direct impact on ocean currents. It is usual to find huge ocean currents circulate around warm and high pressure areas that are the product of the this phenomenon.

A good example would be a plane in flight. Say, a flight is cruising from LA to New York. If there is no Coriolis Effect, the plane would simply fly straight to the east. However, because of this effect, the plane has to be constantly monitored to ensure that it is flying in sync with the earth's movement below. If the plane is left unattended, it would reach somewhere south, not New York.

Although not a new phenomenon anymore, the Coriolis Effect can still make it to technology news sections of science books if not properly interpreted or understood.