What are the causes of ocean currents? How do currents affect the temperature of a region?

Ans. An Ocean current refers to a continuous movement of water in the ocean. They are like large rivers in the oceans with regular volume of water which has a definite path and direction.

Factors which impact the ocean current formations are:

Insolation: Insolation causes the expansion of water molecules. Hence, water near the equator is about 8 cm higher in level than middle latitudes. It causes slight gradient water to flow down the slope.

Wind: The friction between the wind and the ocean surface generates stress, which transfers momentum to the water and causes it to move. Wind-driven currents or surface currents are primarily responsible for the horizontal movement of water in the ocean. For example, the Gulf Stream Current has a similar path as that of westerlies.

Salinity: Waters of low salinity have lower density enabling them to flow on the surface of waters of high salinity while waters of high salinity flow at the bottom.

Coriolis Force: Coriolis forces deflect winds and freely moving objects to the right in the northern hemisphere and to the left in the southern hemisphere. This deflected air causes the water to move accordingly. This leads to formation of gyres in both the hemispheres.

Landmass: A landmass obstructs the direction of flow of ocean current and divides the ocean current to flow in a different direction.

Effects of ocean currents on temperature of regions:

Warming effect by warm current: It makes the port operable near the adjacent areas in comparison to areas lying on the same latitude but at the locations where cold current flows. For example: Norway ports are operable in winter whereas ports in Russia freeze.

Cooling effect by cold current: Cold ocean currents can have a cooling effect on the adjacent regions. For example: As the California Current moves southward, it brings cold waters from higher latitudes, which have a cooling effect on the coastal regions. Further, Cold ocean currents contribute to aridity. Thus, the majority of the deserts are located in their influential area.

Meeting of Cold and Warm Currents: Mixing warm and cold water can create favorable conditions for the growth of phytoplankton, which forms the basis of the marine food chain. For example: The meeting of the Gulf stream (warm) and Labrador (cold) currents near the coast of Newfoundland creates a nutrient-rich zone that supports a thriving fishing industry.

Not only are there a number of factors which impact the formation of ocean currents, but also the ocean currents themselves play a major role in determining regional as well as global climate. Ocean currents have several important uses and they play a significant role in regulating the climate, transportation and navigation, renewable energy generation, fishing and environmental research.