UPSC Static Quiz – Geography : 11 June 2026

Solution: D

• Agulhas Current (A): This is a major western boundary current. It flows down the east coast of Africa, which places it in the Indian Ocean (3). As it flows from the tropics towards the south, it carries warm equatorial water. Therefore, it is a Warm (Y) The correct combination for A is 3-Y.
• Oyashio Current (B): This is a subarctic current that flows south along the east coast of Russia’s Kamchatka Peninsula and the Kuril Islands, meeting the warm Kuroshio Current off the coast of Japan. It originates in the cold Arctic and Bering seas, placing it in the North Pacific Ocean (1). Because of its origin, it is a Cold (X) The correct combination for B is 1-X.
• Canary Current (C): This is an eastern boundary current, part of the North Atlantic Gyre. It flows southwest along the coast of Northwest Africa (near the Canary Islands). It is a continuation of the North Atlantic Current, but as it flows towards the equator, it brings cooler water from the north into warmer latitudes, making it a Cold (X) current relative to the surrounding waters. It is located in the North Atlantic Ocean (2). The correct combination for C is 2-X.

Solution: D

• (a) Langmuir circulations are small-scale, shallow, wind-driven circulations that create parallel streaks of foam and debris on the water surface. They are not the large, basin-wide systems in question.
• (b) Thermohaline circulation refers to the deep-ocean currents that are driven by differences in water density, which is controlled by temperature (thermo) and salinity (haline). This is also known as the global conveyor belt. While it is a major component of ocean circulation, it is a deep-water, density-driven system, not the large, circular surface system driven by winds.
• (c) Ekman spiral is the theoretical model that describes how wind-driven surface water sets water layers below it in motion, with each successive layer moving slower and being deflected further by the Coriolis effect, creating a spiral pattern with depth. While the Ekman spiral is a crucial concept for understanding how wind energy is transferred to the water column, the large circular system itself is called a gyre.
• (d) Oceanic gyres is the correct term. The major ocean basins are characterized by large, rotating current systems called gyres. There are five major subtropical gyres (North Pacific, South Pacific, North Atlantic, South Atlantic, and Indian Ocean). They are formed by the interplay of global wind patterns (like the trade winds and westerlies), the Coriolis effect which imparts a circular motion (clockwise in the Northern Hemisphere, counter-clockwise in the Southern Hemisphere), and the presence of continental landmasses that constrain the flow.

Solution: A

• Statement 1 is incorrect. While the equatorial region receives high insolation, the zone of highest sea surface temperature is typically found slightly north of the geographical equator. This is due to the influence of ocean currents and prevailing winds, which tend to shift the zone of maximum heating, known as the Intertropical Convergence Zone (ITCZ) or thermal equator, to the north.
• Statement 2 is incorrect. In the low and middle latitudes, the western parts of the oceans are significantly warmer than the eastern parts. This is due to the circulation in the major oceanic gyres. Warm equatorial currents flow westward, and upon reaching the western boundary of the ocean basin, they are deflected poleward (e.g., Gulf Stream, Kuroshio Current), carrying warm water to higher latitudes. Conversely, cold currents flow from high latitudes towards the equator along the eastern boundaries of the oceans (e.g., Canary Current, California Current), making these regions cooler.
• Statement 3 is correct. The Northern Hemisphere is often called the “land hemisphere” due to the greater proportion and more complex distribution of landmasses compared to the Southern Hemisphere (the “water hemisphere”). Land heats up and cools down much faster than water (differential heating). This strong land-sea contrast in the Northern Hemisphere disrupts the otherwise latitudinal pattern of temperature, causing the isotherms (lines of equal temperature) to be much more irregular and to bend significantly when they cross from ocean to land. In the more uniform oceanic expanse of the Southern Hemisphere, the isotherms are more regular and parallel to the latitudes.

Solution: A

• Statement-I is correct. Narvik, a major port in northern Norway, is located at approximately 68-degree N latitude, which is about 220 km inside the Arctic Circle. Despite this high latitude, where one would expect severe sea ice in winter, its harbor remains open and navigable year-round. This is a crucial factor in its economic importance, particularly for the export of iron ore.
• Statement-II is also correct. The Gulf Stream is a powerful warm current originating in the Gulf of Mexico. As it flows across the Atlantic, it becomes the North Atlantic Drift. This current transports a massive amount of heat from the tropics towards the northeast, significantly warming the seas and moderating the climate of Northwestern Europe, including the British Isles and the coast of Scandinavia.
• Statement-II provides the direct and primary reason for the phenomenon described in Statement-I.

Solution: C

• The normal condition in the ocean is for temperature to decrease with depth, at least in the upper layers. A layer where temperature decreases rapidly is the thermocline.
• (a) A pycnocline is a layer where density increases rapidly with depth. An inversion would mean density decreases with depth, which is a highly unstable and rare condition.
• (b) A halocline is a layer where salinity changes rapidly with depth. While salinity affects temperature, a “halocline anomaly” is not the standard term for a temperature inversion.
• (c) A thermocline inversion, or simply a temperature inversion, is the correct term for the condition where colder water overlies warmer water. In high-latitude oceans, this can happen during the formation of sea ice. As seawater freezes, it expels salt, making the remaining surface water not only very cold but also very saline and dense. However, under certain conditions, meltwater from glaciers or ice sheets can form a fresh, cold layer on the surface that is less dense than the slightly warmer, more saline water beneath it. This creates a stable stratification with colder water on top, which is a form of temperature inversion.
• (d) A surface tension lapse is not a recognized oceanographic term. Surface tension is a property of the water’s surface and is not related to the vertical temperature profile.