Causes of Ocean Currents: Planetary winds, Rotation of earth and Other

Causes of ocean currents


Let us learn about the factors that are the main causes of ocean currents.


How are ocean currents formed?


Oceanic currents are formed by the interaction of a number of factors. Here are the 5 causes of ocean currents.

� Planetary winds
� Variation in seawater temperatures
� Variation in water salinity
� Rotation of earth
� Configuration of the coastlines


1. Planetry winds:

Planetary winds are one of the most important causes of ocean currents. The planetary winds blow continuously in a particular direction and drag the surface water due to the force of friction. This leads to the formation of ocean currents. Most of the ocean currents of the world follow the direction of prevailing or planetary winds.

For example, equatorial currents flow westward under the influence of northeast and southeast trade winds. The North Atlantic Drift in the Atlantic and the North Pacific current in the Pacific move in the northeast direction under the influence of westerlies.


2. Variation in seawater temperatures:

These are marked variations in the horizontal and vertical distribution of temperatures of the oceans. The temperatures are higher at the equator than at the poles. Thus, in the equatorial region, the density of water decreases due to high temperatures and more rainfalls. As a result of this, the lighter water from the equatorial region moves towards the colder and denser water of the polar areas.


3. Variation in water salinity:

The amount of salts contained in seawater does vary from one part of the ocean to another. The high salinity water tends to subside and move below the water of low salinity. Ocean currents on the water surface are generated from the areas of low salinity to the areas of high salinity. There is a marked variation in the salinity of the Atlantic Ocean and the Mediterranean sea. Do you know what is salinity?


Salinity is the saltiness of an ocean. Because of this variation, the ocean current flows from the Atlantic Ocean to the Mediterranean Sea.


4. Rotation of the Earth:

The earth rotates on its axis from west to east. This rotation is the cause of deflective force known as Coriolis force which deflects the general direction of the winds and that of the ocean currents. For example, the currents flowing from the Equator towards the North and South Poles are deflected to their right in the Northern Hemisphere and towards their left in the Southern Hemisphere. The counter-equatorial currents are also the result of the rotation of the earth.


5. Configuration of the Coastlines:

The shape and configuration of the coastlines also have a close influence on the direction and movement of the ocean currents. In the Indian Ocean, the monsoon currents closely follow the coastlines.


Causes of Ocean Currents MCQs


1. Which of the following is not a factor responsible for the formation of ocean current?
a. Planetary winds
b. Rotation of earth
c. Variation in water salinity
d. Revolution of earth


2. The temperatures are higher at the equator than at ______.
a. Land
b. Ocean
c. Core
d. Pole


3. Planetary winds drag the surface water due to the force of __________
a. Gravitation
b. Rotation
c. Wind
d. Friction


4. The currents flowing from the Equator towards the North and South Poles are deflected to their right due to
a. Frictional forces
b. Gravitational forces
c. Thermal forces
d. Colioris forces


5. Salinity is the _____________ of an ocean
a. Density
b. Mass
c. Length
d. Saltiness

Read More: What are Ocean Currents: Two Types - Warm Currents and Cold Currents

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