Explain the factors responsible for the origin of ocean currents. How do they influence regional climates, fishing and navigation?
Answers
Primary factors are responsible for the origin whereas the secondary factors determine the direction of flow of ocean currents.
Primary causes:
Planetary winds: Planetary winds are the principal cause of the origin of ocean currents. Such winds drive surface water along with them.
Difference of density and salinity: Difference of density and salinity in ocean water motivates denser waters to sink and move as undercurrents; whereas lighter waters move towards the denser water as surface currents. Such density differences are mainly the result of differences in temperature and salinity of ocean waters.
Secondary causes:
The rotation of the Earth: The rotation of the Earth, which affects the direction of movement, deflects poleward current eastwards, equator wards currents westwards. It may be pointed out here that the wind induced surface current deflects 45° or less from the wind direction so that the deflection of ocean currents are much more than the deflection of wind caused by Earth’s rotation
The shape of the coastline: The shape of the coastline of the ocean basins often deflects currents from their direct courses Ocean currents act much like a conveyer belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics.
Thus, currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth’s surface. Without currents, regional temperatures would be more extreme—super hot at the equator and frigid toward the poles—and much less of Earth’s land would be habitable.
Places where cold and warm currents meet are ideal for the growth of Plankton. These are very small organisms, which are food for fish. These regions thus support a great number of fish. They have developed into major fishing grounds of the world. Newfoundland on the eastern coast of North America is the meeting point of the Gulf Stream and the Labrador Current. It is one of the major fishing centers of the world. However, these places may be dangerous for ships as the meeting of cold and warm currents gives rise to thick fog, which reduces visibility.
Ships sailing with a current, gains speed which helps to save fuel and time. Ships moving against a current lose speed.
Warm currents keep the Arctic regions free from icebergs, which can be dangerous for ships. In this way ocean currents have impact on climate, fishing as well as on navigation