Coriolis Effect

The Coriolis effect is the apparent curvature of ocean currents, winds, and anything else that moves along or on the Earth’s surface. It is caused by the Earth’s rotation. Although an extremely important concept in physics and geography, it is often misunderstood. A manifestation of this is that, people believe it to be responsible for the water in a drain, swirling in a particular direction in the northern hemisphere, and in a different direction in the southern hemisphere. This is not true, because the effect has nothing to do with water swirling in the drain, that is solely down to the shape of the drain.

What is the Coriolis Effect?

This phenomenon is best explained as the tendency of any moving object, on or above the Earth’s surface, to stray sideways from its normal course, due to the Earth’s rotation. The deflection is towards the left in the southern hemisphere, while in the northern hemisphere, it is towards the right of the usual motion. Gaspard Coriolis, a French engineer, discovered this phenomenon and also came up with mathematical formulas to explain it.

The Earth’s surface does not rotate at all, at the poles, while the rotation speed is maximum along the equator. This is the reason why objects moving further from the equator drift eastwards, while the ones moving closer to the equator tend to drift westwards. All movements on or above the Earth’s surface, like winds, water flow, even artillery fired in the air, and ocean currents, are subject to this phenomenon.


The Earth’s rotation is known to be the main cause of the Coriolis effect. The Earth spins in an anticlockwise direction on its axis, and because of this, objects moving on or above the surface over a long distance, are deflected, as they are moving in the opposite direction, and that too at a faster speed.

The Earth’s rotation speed decreases with latitude, while this effect increases. When a plane flies above the equator, it would continue moving without any major deflection. However, if the plane flies even a little away from the equator, the plane is sure to drift, and the drift is maximum at the poles.

Hurricanes are never formed along the equator, as there is not much of an Coriolis effect there. Storms formed north of the equator develop into hurricanes, as they start rotating and gaining strength. Apart from the distance from the equator and the Earth’s rotation, speed of the moving object also determines the extent of this phenomenon. Faster the object, more the deflection. Also, on which side of the equator the object is present, determines the direction of its drift.


The most crucial impact of the Coriolis effect is on the ocean currents and wind directions. Apart from this, planes, artillery, and missiles, are certain man-made objects which are affected by this phenomenon. Its impact on wind patterns is very prominent. When air rises up from the Earth’s surface, its speed is greater than otherwise. This is because the air now does not have to move across the various landforms on the surface and as a result, its drag reduces. As faster moving objects have a greater Coriolis effect, the rising air is deflected, forming winds.

As the wind traveling across the ocean water helps in formation of ocean currents, the effect also has a bearing on the movement of ocean currents. Huge ocean currents circulate around high pressure and warm areas, formed mainly due to the deflection caused by this phenomenon. Deflecting bullets, missiles, and planes, are also a result of the same.

For instance, assume that a flight is traveling from Los Angeles to New York. If there was no rotation of the Earth, there would be no Coriolis effect and plane could travel straight to the east, but because of it, the plane movement needs to be constantly monitored so that it is in sync with the Earth’s movement below. If it is left to fly straight, the plane would reach somewhere south.

Coriolis effect is therefore an indispensable tool when it comes to understanding many important concepts of physical geography.

Earth’s Core

The earth’s core is both, solid and molten, and is believed to be cooling down gradually. The iron-nickel composition within is responsible for the electromagnetic field generated around the planet and the consistent seismic activity observed. Earth, the planet we inhabit, is the third from the sun. It is not only the largest terrestrial planet in the solar system, but also ranks in terms of mass, diameter and density. Our planet is home to millions of living species and is the only planet known to support life. Formed more than 4.50 billion years ago, the biosphere has consistently altered its atmosphere and abiotic conditions. The presence of aerobic organisms, the ozone layer, and the magnetic field, all make the planet unique.

Vital Information

The planet’s outer surface or crust is made up of a number of segments or tectonic plates. These plates migrate over the surface, which is covered by 71% water and 29% land. The interior is persistently active and homes a layer of solid mantle, liquid outer, and an inner core that is concentrated in iron content. This is the reason behind the magnetic field generated around the planet. The planet’s mineral resources, biosphere components, their interdependency, and the presence of water are responsible for the survival of life forms.


The earth is an oblate spheroid. It is a sphere that bulges around the equator. With a mass of 5.98 × 1024 kg, the planet is composed of iron, oxygen, silicon, magnesium, sulfur, nickel, calcium, aluminum, and traces of other elements. The core is mainly composed of iron, nickel, and sulfur. Its interior is subdivided into chemical and physical layers, each with its own unique properties. The solid outer crust is held in place by a solid mantle that is viscous in nature. Beneath this mantle region, lies a liquid, outer part that protects a solid, inner, molten one that displays angular velocity. These two layers make up the total core of the planet.

How Hot Is the Core?

The inner center of our planet has a temperature that could rise beyond 10,340.33°F and the generated pressure could build up to more than 300 GPa. Volcanic activity and seismic waves contribute to and arise from these extreme conditions. It is about 1,220 km in radius, and primarily comprises an iron-nickel alloy. The temperature within it is believed to be similar to that on the sun’s surface. Very little is actually known about its inner part. It is believed that the region is gradually cooling to a homogeneous, clean layer. However, seismologists reveal that it enables the passage of seismic waves rapidly, in all directions. The molten inner center is believed to be composed of layers. Each of these is separated by some sort of transition zone.

Why Is the Core So Hot?

The outer center does not have the ability to allow shear waves to pass through, and hence, compressional waves are generally observed in the region. The composition of the inner part, a nickel-iron alloy, is what makes the region very hot. These elements keep heating at the high temperature ‘locked’ within, with even the iron content melting at the dramatically high pressure generated. Research reveals that there is a super-rotation of seismic waves within the inner crux, and this property is responsible for one degree of extra rotation every year. The composition and trapped heat within the region is what generates a magnetic field due to a dynamo action. The dynamo action is generated within the liquid, outer surface.

This was a short summary about the earth’s core. It is important to know about this topic in order to have general awareness about our planet and the problems it is facing.