Ocean currents are driven by wind, water density differences, and tides. These describe the movement of water from one location to another. What are ocean currents? How do they affect the climate?

 

Movements in the oceans

 

The water of the oceans and seas is never at rest. It keeps on moving constantly. But what are these movements?

 

There are three types of movements in oceans:

 

i. Waves: The up and down movements seen on the surface of ocean water are known as waves. The pushing action of the winds blowing over the ocean is the most important cause of the waves. Due to the push of the winds, the particles of water move up and down and pass on their movement to the immediate next particles. Water, therefore, rises and falls in a wave.

 

ii. Tides: Tides are the periodical rise and fall of sea level due to changes in the attractive forces of the Moon and Sun.

 

iii. Ocean current

 

What are Ocean Currents?

Ocean currents are defined as the large-scale movements of water in the oceans in a definite direction. If the mass of the water moving on the surface of an ocean is broad, slow, and shallow, it is termed drift. But how do we measure ocean current?

 

Currents are generally measured in meters per second or in knots.1 knot = 1.85 kilometers per hour or 1.15 miles hour

 

There are two kinds of currents:

 

1. Warm currents: The current that originates near the equator and flows towards the poles is called a warm current.
2. Cold currents: The current that originates in the high latitudes and flows towards the equator is called a cold current.

 

Ocean currents have considerable influence on the climate, agriculture, and other economic activities of the coastal regions and islands near which they flow. But what are these impacts?

 

1. The warm current makes the climate warmer. For example, the Kuroshio current in the Pacific Ocean and the Gulf Stream in the Atlantic Ocean modify the climates of southern Japan and the eastern part of the USA respectively.

 

2. The warm current keeps the ports or even polar regions free from ice during winter. For example, the coast of Norway within the Arctic circle remains free from ice even during winter due to the warm North Atlantic Drift. On the other hand, due to the cold Labrador Current, the Labrador coast remains frozen.

 

3. The current even have an influence on the amount of rainfall received by a country. Countries influenced by warm currents, like Ireland, Britain receive more rainfall because winds passing over there absorb a lot of moisture and on the other hand, the Atacama desert in South America remains dry because the winds pass over cold currents and are unable to pick up the moisture.

4. The mixing of warm and cold currents helps in the production of planktons. Hence they support fish in large numbers and are important fishing grounds of the world. Do you know what are planktons? These are minute sea organisms that provide food for fish.

 

5. The mixing of warm and cold currents produces very thick fog over the area. This is very dangerous for ships as visibility is reduced. One such region is near Newfoundland where the warm Gulf Stream meets the cold Labrador current.

 

6. The currents influence navigation also. A ship sailing down the current will surely go faster. So it can save time and fuel.

 

7. The warm currents also help in melting icebergs which are dangerous for ships.

 

Questions:

 

1. Which of the following is not a type of movement in oceans?
a. Waves
b. Tides
c. Ocean current
d. Erosion

 

2. Wave is the _______________ movements seen on the surface of ocean water.
a. To and fro
b. Left and right
c. Up and right
d. Up and down

 

3. Which of the following is not a unit in which the ocean current is measured?
a. Metre per second
b. Kilometer per hour
c. Miles per hour
d. Yards per hour

 

4. Which of the following group most appropriately represents the kinds of currents?
a. Upwards and downwards current
b. North and South current
c. Vertical and Horizontal current
d. Warm and cold current

 

5. Kuroshio current is an example of ________current.
a. Cold
b. Vertical
c. Horizontal
d. Warm