Test: The Oceans - UPSC MCQ

The Pacific Ocean is the largest ocean on Earth, occupying approximately one-third of the planet's surface. It is larger than all the continents combined.

The Atlantic Ocean is known for its extended S shape and connects continents such as Africa, Europe, the Arctic Ocean, the Americas, and the Southern Ocean.

The Indian Ocean is considered the hottest among the major oceans. It is surrounded by land in the northern hemisphere and is located between Asia, Australia, the Southern Ocean, and Africa.

The Southern Ocean is collectively referred to as the Antarctic Ocean or Austral Ocean. It surrounds Antarctica south of 60°S latitude and is the second-smallest and fourth-largest ocean in the world.

The Arctic Ocean has the lowest average salinity among the major oceans. It is also shallower and smaller compared to the other four oceans.

The temperature distribution in the oceans is influenced by factors such as latitude (as one moves away from the poles, the temperature of surface water drops), uneven distribution of land and water (northern hemisphere's oceans experience greater heat due to larger land area), prevailing winds (drive warm surface water away from the coast or pile up warm water near the coast), and ocean currents (warm currents raise temperature in cold areas, while cold currents decrease temperature in warm areas).

Salinity refers to the amount of salt (in grams) dissolved per kilogram (1000 g) of seawater. It is an important property of seawater and is usually expressed as parts per thousand (ppt) or °/₀₀.

The highest salinity in the oceans is generally observed between 20° and 30° N and S latitudes, which are characterized by high temperatures, high evaporation, and less rainfall compared to the equatorial region.

The layer in the ocean where there is a sharp increase in salinity is called the halocline. It is one of the three distinct zones found between 300 m and 1000 m depth of ocean water, along with the pycnocline (density gradient) and thermocline (temperature gradient).

The bottom layer of the ocean carries about 80% of the total volume of ocean water. It has the highest but uniform density compared to the other layers, such as the surface layer of lowest density and the pycnocline layer of sharp density gradient.