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Ocean Currents – Various Types, Causes, Effects

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  • Last Updated : 28 Mar, 2022

The nature of ocean water is dynamic. Different types of ocean currents flow in a certain direction, almost continuously through the surface of different seas and oceans of the earth. Ocean currents make up horizontal and vertical components of the circulation system of ocean water. The horizontal motion of Ocean water refers to currents and waves whereas the vertical motion refers to tides. It is similar to winds flow in the atmosphere.  But the speed of the ocean current is not as fast as the wind. The average speed of the ocean current is 3 to 9km/hr. The speed of the shallow ocean current is competitively higher than that of the deep ocean. It helps to transfer heat from Earth’s equatorial areas to the poles. It also plays a vital role in determining the climates of coastal regions. Thus atmospheric circulation and ocean current influence each other. 

What is Ocean Current?

On account of earth rotation, wind flow, the salt density of the seawater, and temperature, seawater regularly flows in a certain direction. This movement of seawater is called Ocean Current. An ocean current flows for great distances. They create the global conveyor belt and play a dominant role in determining the climate of many regions of the Earth.

Types of Ocean current:

There are different types of Ocean currents. These types are discussed below:

1. Warm Ocean currents:

Warm Ocean currents are large masses of warm water. It is moving further away from the equator with higher temperatures. Warm ocean current forms when salty cold water becomes heavy and sinks. In this process, warm and lighter water moves in the opposite direction. When an ocean current flows from the tropical region, the current is called the warm Ocean current.

Example:  

a) Brazil current: The South branch of the Benguela Current and the south equatorial current flows along the east coast of Brazil, called the Brazil current, and reunites with the Antarctic current. It is an Antarctic ocean current.

b) Tsushima current: It is a tributary of the Japan stream, called the Tsushima current, and flows along the west coast of Japan. It is a Pacific Ocean current.

c) Madagascar current: It is a combination of western Australian current and South Equatorial current. Madagascar current is an Indian Ocean current.

2. Cold Ocean currents: 

Cold ocean currents are large masses of cold water that move towards the equator. It moves from a level of high altitude to a lower altitude. They absorb the heat from the tropics and thereby cooling the air above them. It forms when the air of the subtropical high region blows over a cold mass of water, and the cold air is stretched out to the equator.

When an ocean current flows through a cold polar region, that current is called a cold current.

Example:

a) Falkland ocean current: A tributary of the Arctic current runs along with the Falkland Islands along the east coast of South America and flows slightly northward, called the Falkland ocean current. It is an Atlantic Ocean current.

b) Peru ocean current or Humboldt Current: It is a branch of the cold polar current rising by the influence of westerly wind of the southern ocean and flows towards the southwestern part of South America. Then it bents to the north and flows down along with the Chile coast by the name of Peru current.

  • Basically, this cold water current moves from the south to the northern part along the coastal region of Chile and Peru in the eastern parts of the South Pacific Ocean region.
  • This phenomenon for the first time was identified by Alexander von Humboldt.
  • In recent years, the phenomenon of EI-Nino has been observed when this cold water current becomes relatively warm.
  • The weather and climate are adversely affected in the year of EI-Nino.

c) West Australian current: A branch of the South polar ocean current flows toward the east by the influence of westerly wind. This ocean current is known as the cold west Australian current. It is an Indian Ocean current.

3. Equatorial currents:

When ocean currents flow from the equatorial province, are called equatorial currents. It flows westward near the equator.

Example: South Pacific equatorial current( between 5 degrees north to 15 degrees south)

4. Surface of Ocean currents:

When an ocean current flows from a warmer region to a cold region, it flows relatively through the upper part of the seawater. This ocean current is called surface Ocean current.

Example: California ocean current. This ocean current has created a huge seaweed.

5. Deep ocean currents:

It generally happens in high-altitude regions. Here the ocean current flows from the cold region to the warm region through the lower part of the seawater. Almost 90% of the ocean make up of this water. 

It occurs in the  North Atlantic Deep Water and Antarctic Bottom Water region. 

Most Common Reasons behind the Ocean current: 

1. Wind flow:

According to modern scientists, wind flow is the main reason behind the Ocean current. In those places where the western wind blows, there, the ocean current flows from the west to the east. It works as a primary force to create ocean currents.

The sun heats perpendicularly at the equator. Due to this, warm and moist air rise into the atmosphere and create a low-pressure area.

the warm and moist air of the equator region travels northward and southward direction.  This air reaches a certain cold temperature, it sinks and a high-pressure area is created.  In the Northern Hemisphere, this air motion creates strong winds flowing from the west, which is called westerlies, and the northeast wind flowing is called the trade wind. Oceanic currents are driven by these wind patterns.

2. Coriolis effect: 

The earth rotates from West to East. Due to this reason, the speed of the ocean currents is deflected like the wind and following Ferrel’s formula, it turns on the right side in the northern hemisphere and turns on the left side in the southern hemisphere. It calls the Coriolis force. In the 19th-century, a French engineer and mathematician, named Gustave-Gaspard Coriolis observed it for the first time. According to his name, this phenomenon is called the Coriolis effect.

3. Different temperatures of the ocean:

The sun’s rays fall somewhere vertically or diagonally on the surface of the seawater. Due to this, the temperature of seawater varies. To maintain the temperature of the ocean, the water of the warm region flows toward the cold region. On the other hand, the water of the cold region flows toward the warm region.

4. Different Salt densities of Ocean:

Ocean currents are also created due to the varying salinity and density of seawater. 

When the salinity of Ocean water becomes high, its density also increases. On the other hand, when the salinity becomes high enough, the water will sink and start a convection current. It means cold water can sit on top of warm water when the warm water has a high enough salinity. This process creates a circular pattern known as a convectional ocean current.

5. Gravity:

the motion of the water of the ocean flowing from higher elevation to lower elevation. This motion is happened due to gravity. The speed and direction of the ocean currents can be measured and recorded.

Oceanic currents are occurred by several factors. One such cause is the rise and fall of the tides. It is driven by the gravitational attraction of the sun and moon on Earth’s oceans. It creates tide and tide is the cause that creates a current in the oceans.  It is called tidal currents. Only  Tidal currents are charged in a very regular pattern. It is occurred due to the gravitational force.

Effect of Ocean current: 

A) Climate control: It’s responsible for moving heat from the Equator to the polar region. Thus it helps to maintain the balance of climate. Ocean currents act as a conveyor belt. It transports warm water from the equator toward the poles and cold water from the poles to the tropics. Even it also helps to distribute solar radiation throughout the Earth’s surface. Without ocean currents, regional temperatures would be more extremely such as the equator becoming super hot and the poles becoming super cool.

B) Control marine life: Ocean current maintains a proper balance of the temperature of ocean water. This type of water produces microscopic plants, called plankton which is the main food of marine life. For this reason, the Grand Banks, New Falkland, the British Island, Norway, and the coast of Japan are rich in fish.

C) Raining: The air flowing over the warm Ocean current is full of water vapor. When the evaporated water flows over the land, it causes rain. A recent study says the Atlantic Ocean affects rainfall in the Western Hemisphere. Due to the warm currents of the Atlantic Ocean, the west coast of England gets rainfall.

D) Snowfall:  When the air flows over the cold Ocean current, it dries up. So that this wind does not cause rainfall but causes snowfall. Due to this reason, Cold Labrador currents increase snowfall on the Labrador coast.

E) Snow-free port: Warm ocean currents melts the ice of the coastal area of the polar region. This facilitates navigation. The Coastal seaports of Norway,  Canada, etc. are the best example.

F) Fog and Storm: Due to the variation of warm and cool ocean currents and for a change of temperature in a small space, Fog and storms are seen at the confluence of the warm and cold ocean currents. Due to these reasons, New Falkland and Japan are foggy almost all around the year.


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