- Explain the various factors responsible for the formation and modifications of ocean currents. How do they influence regional climates, navigation and fishing. [200 words]
The regular movement of a volume of oceanic water in a definite direction & path is called ocean currents. Following are the factors responsible for the creation and modification of ocean currents:
Influence of isolation
- Heating by solar energy causes the water to expand. That is why, the ocean water is about 8 cm higher in level near the equator than in the middle latitudes.
- This causes a very slight gradient and water tends to flow down the slope. The flow is normally from east to west.
Prevailing Planetary Winds
- Wind blowing on the surface of the ocean pushes the water to move. Friction between the wind and the water surface affects the movement of the water body in its course.
- Example- seasonal change in the direction of currents in the Indian Ocean twice a year due to seasonal change in the direction of monsoon winds.
Influence of gravity
- Gravity tends to pull the water down to pile and create gradient variation.
Influence of Coriolis force
- The Coriolis force intervenes and causes the water to move to the right in the northern hemisphere and to the left in the southern hemisphere.
- One such circular current can be seen at the Sargasso Sea.
Secondary Factors Responsible For Ocean Currents
Difference in temperature, salinity and density are also responsible for the existence of ocean currents.
- As a rule, water moves from the areas of the lower density to the areas of higher density.Density variation can be due to pressure, temperature or salinity differences.
- High temperature at equator due to isolation decreases the water density, while low temperature increases it on the poles. Consequently, water moves due to expansion of volume from equatorial region to polar areas.
- Oceanic Water high salinity is denser than water with low salinity and in the same way cold water is denser than warm water. This density variation causes ocean currents.
Factors Responsible for Modification of ocean currents
- Direction, Shape and configuration of coastlines
- Bottom reliefs
- Seasonal variation (E.g. Monsoon)
Impact of Ocean Currents on the Following
- The displaced warm water raises the temperature of the air while the cold water cools the air, and the land surface where the blows.
- For instance, water from the tropical Atlantic moves northwards through Atlantic in a Gulf Stream suffusing the Western Europe’s shores thus producing a mild climate. The mild climate raises the temperatures of the region higher than the regions across the Atlantic but on the same latitude.
- Currents are referred to by their “drift”. Ships usually follow routes which are aided by ocean currents and winds. Ships sailing with a current, gains speed which helps to save fuel and time.
- Mixing of cold and warm ocean currents are ideal for the growth of Plankton, the primary food for fish. The best fishing grounds of the world exist mainly in these mixing zones.
- Example: Grand Banks around Newfoundland, Canada and North-Eastern Coast of Japan.
(P.S.- The above question is a bit lengthy and probabilities of such lengthy questions are very less considering UPSC word limit is concerned. However, you can break it into 2 separate questions, one as the factors for the creation of the ocean currents and second being its impact on certain entities. Again, try to incorporate at least one example while describing a phenomenon in Geography, which shouldn’t be redundant in description.).
- On the planet earth, most of the freshwater exists as ice caps and glaciers. Out of the remaining freshwater, the largest proportion
a. is found in atmosphere as moisture and clouds
b. is found in freshwater lakes and rivers
c. exists as groundwater
d. exists as soil moisture
DAILY CURRENT AFFAIRS
- Which of the following article provides the Governor with the power to remit or commute the sentences of any prisoner in certain cases?
a. Article 158
b. Article 161
c. Article 163
d. Article 162
- Andhra Pradesh, Odisha and Madhya Pradesh have been awarded the three best performing states in the ‘Ease of Living Index’ rankings under AMRUT (Atal Mission for Rejuvenation and Urban Transformation). Which of the following is/are an indicator to determine ‘Ease of Living Index’:
2. Economy and Employment
3. Solid Waste Management
4. Waste Water Management
a. 1 only
b. 2 & 3 only
c. 1 & 2 only
d. All of the above