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Ocean Currents

Ocean currents are the continuous, predictable, directional movement of seawater. It is a massive movement of ocean water that is caused and influenced by various forces....
What are Ocean Currents?
  • Ocean currents are the continuous, predictable, directional movement of seawater. It is a massive movement of ocean water that is caused and influenced by various forces. They are like river flows in oceans.
  • Ocean water moves in two directions: horizontally and vertically.
    • Horizontal movements are referred to as currents, while vertical changes are called upwellings or downwellings.
Which are the Factors that Influences Ocean Current?
(a) Movement of Ocean Water
  • The water in the ocean is never still.
  • Diverse forms of ocean water flows exist as a result of different physical qualities such as temperature, salinity, density, and so on.
  • External influences such as the sun, moon, and winds influence the movement of ocean water.
  • The major movements of ocean waters can be divided into three categories. They are as follows:
    1. Waves
    2. Tides
    3. Ocean Currents
(b) Secondary forces:
  • Differences in water density: It affects vertical mobility of ocean currents
  • Temperature of water: Cold-water ocean currents occur when the cold water at the poles sinks and slowly moves towards the equator.
What are the Types of Ocean Currents?
  • Surface currents: Large-scale surface ocean currents are driven by global wind systems that are fueled by energy from the sun.
  • Deep water currents: Differences in water density, resulting from the variability of water temperature (thermo) and salinity (haline), also cause ocean currents. This process is known as thermohaline circulation.

Ocean currents can also be classified based on temperature:

  • Cold currents: It brings cold water into warm water areas.

These currents are usually found on the west coast of the continents in the low and middle latitudes and on the east coast in the higher latitudes in the Northern Hemisphere.

  • Warm currents: It brings warm water into cold water areas and is usually observed on the east coast of continents in the low and middle latitudes
What are the Effects of Ocean Currents?
  1. Climatic Conditions : The warm Equatorial currents raise the temperature of the region in which they flow. The cold currents lower the temperature of the places where they flow
  2. Rainfall: The winds blowing over warm currents pick up and carry moisture and bring rainfall like the North Atlantic Drift brings rainfall in some areas located along the western coasts of Europe.
  3. Fog Formation: The meeting of the warm and the cool currents results in the formation of fog.
  4. Creates Fishing Zone: The mixing of warm and cold currents results in the deposition of planktons. Therefore, at such places, fishes can be found in abundance.
  5. Desert formation: Cold ocean currents have a direct effect on desert formation in west coast regions of the tropical and subtropical continents.
  6. Violent Storms: At times the meeting line of a warm and a cold current may result in a violent storms.
What are the significance of Ocean Currents ?
  • Ocean currents play a significant role in climate management by transporting heat from the equator to the poles.
  • The importance of ocean currents to sea life cannot be overstated.
  • They transport nutrients and food to creatures that are firmly linked to a single location, as well as reproductive cells and ocean life to new locations.
a) Waves
  • The oscillatory movements that cause the rise and fall of the water surface are known as waves.
  • Waves are horizontal movements of water in the ocean.
  • They are the energy that travels across the ocean surface, not the water itself.
  • The wind provides the energy for the waves.
  • Each water particle moves in a circular motion during a wave.
  • The rising portion of a wave is known as the crest, while the low point is known as the trough.
b) Tides
  • The combined effects of the gravitational forces exerted by the sun, the moon, and the rotation of the earth create the periodic rise and fall of the sea levels, once or twice a day which is called a tide.
  • Type of vertical water flow that differs from ocean water movements induced by meteorological factors such as winds and atmospheric pressure variation
  • The moon’s gravitational pull is a key contributor to the occurrence of tides (the moon’s gravitational attraction is stronger on the earth than the sun’s).
  • Other forces that combine with the moon’s gravitational pull include the sun’s gravitational pull and the centrifugal force caused by the earth’s rotation.
  • The Bay of Fundy in Canada has the world’s highest tides.
  • The time between two high or low tides is 12 hours 25 minutes on average.
c) Ocean Currents
  • The horizontal movement of a mass of water in a sufficiently defined direction across long distances is known as ocean currents.
  • They resemble a river moving across an ocean.
  • Winds, density changes in ocean waters due to temperature and salinity variances, gravity, and events such as earthquakes can all contribute to the formation of ocean currents.
  • The rotation of the planet has a significant impact on the direction of an ocean current’s flow (due to Coriolis force, most ocean currents in the northern hemisphere move in a clockwise manner and ocean currents in the southern hemisphere move in an anti-clockwise manner).
  • Gyre is a huge system of rotating ocean currents, especially those associated with strong wind motions. The Coriolis force is responsible for them.
  • Drift is the movement of ocean water ahead under the influence of the prevailing wind (the term ‘drift’ is also used to refer to the speed of an ocean current measured in knots). Eg: North Atlantic Drift.
  • Stream is formed when a vast body of ocean water moves in a particular route, similar to a large river on land. They will travel faster than drifts. Eg: Gulf Stream.

Read More : Oceanography

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