Which of the following is/are NOT a cold ocean current ? 1. Agulhas current 2. Brazil current 3. Humboldt current 4. California current Select the correct answer from the code given below : Code :
- (a)1 and 3
- (b)2 and 3
- (c)3 and 4
- (d)1 and 2
Correct — D, 1 and 2: the Agulhas Current and the Brazil Current are the two that are NOT cold. Both are warm currents, and they are warm for the same structural reason. Each is a western boundary current — it runs along the western edge of an ocean basin, which is the eastern coast of a continent — and western boundary currents carry tropical water polewards. The Agulhas is the warm current of the south-west Indian Ocean, sweeping south down the coasts of Mozambique and South Africa before turning back on itself in the celebrated Agulhas retroflection. The Brazil Current is its South Atlantic counterpart, running south along the Brazilian coast until it collides with the cold Falkland or Malvinas Current in the confluence off Argentina, one of the sharpest temperature fronts in any ocean. The other two in the list are genuinely cold. The Humboldt Current, also called the Peru Current, flows equatorward up the coasts of Chile and Peru and drives the upwelling that feeds one of the world's largest fisheries; the California Current flows equatorward down the coast of the western United States. Both are eastern boundary currents, and eastern boundary currents are cold, broad and slow, drawing water from higher latitudes and pulling cold water up from below along the coast. So the two that are not cold are 1 and 2, and on this paper that is option (d).
- (a)1 and 3 — Half right and half wrong. The Agulhas does belong in the answer, since it is warm, but the Humboldt Current does not: it is one of the coldest and most important cold currents on Earth, an equatorward eastern boundary current whose upwelled water supports the Peruvian anchoveta fishery and helps keep the Atacama desert dry. Including it in a list of currents that are not cold reverses one of the most heavily taught facts in physical geography.
- (b)2 and 3 — The same mistake with the other warm current. The Brazil Current is correctly identified as not cold, but the Humboldt Current is cold — a candidate who marks this has recognised one western boundary current and then failed to notice that the second name in the option is an eastern boundary current on the opposite side of South America. The Brazil Current runs down the Atlantic side and is warm; the Humboldt runs up the Pacific side and is cold. They are almost a matched pair for teaching the contrast.
- (c)3 and 4 — This is the trap the question was written for, and it is the answer to the opposite question. Humboldt and California are exactly the two cold currents in the list, so a candidate who identifies them correctly and then forgets that the question asks which are NOT cold will mark this option with complete confidence. It is worth pausing over: the geography here is perfectly understood and the mark is still lost, purely on the negation.
Surface ocean currents are driven mainly by the prevailing winds and organised by the Coriolis effect into great rotating gyres — clockwise in the northern hemisphere, anticlockwise in the southern. Because a gyre turns, its two flanks behave differently. On the western side of an ocean basin, which is the east coast of a continent, water is pushed away from the equator, so western boundary currents are warm; they are also narrow, deep and fast, the Gulf Stream, Kuroshio, Brazil, Agulhas and East Australian currents being the standard examples. On the eastern side of a basin, which is the west coast of a continent, water returns towards the equator from higher latitudes, so eastern boundary currents are cold; they are broad, shallow and slow, and offshore-directed wind stress along these coasts drives upwelling that brings still colder, nutrient-rich water to the surface. The Canary, Benguela, California and Humboldt currents are the classic four. That single rule of thumb answers most exam questions of this type without any memorisation of individual names.
Two habits settle this question. The first is to convert every current name into a position on the map before judging its temperature: Agulhas is off south-east Africa, Brazil is off eastern South America, Humboldt is off western South America, California is off western North America. The first two are on east coasts, hence warm; the last two are on west coasts, hence cold. The second habit is to underline the word NOT the moment you see it and to write the direct answer in the margin first. Here the cold currents are 3 and 4, so the currents that are not cold are 1 and 2 — and option (c), which prints 3 and 4, is sitting on the page waiting for anyone who skipped that step. Examiners in every commission use this device, and it costs more marks than any amount of ignorance about oceanography. A useful memory hook: cold currents tend to sit beside the world's coastal deserts — the Atacama beside the Humboldt, the Namib beside the Benguela, the Sahara's western edge beside the Canary — because cold water suppresses evaporation and stabilises the air above it.
- Western boundary currents run along the east coasts of continents and are warm, narrow, deep and fast — the Agulhas, Brazil, Gulf Stream, Kuroshio and East Australian currents
- Eastern boundary currents run along the west coasts of continents and are cold, broad, shallow and slow — the Humboldt (Peru), California, Canary and Benguela currents — and they are associated with coastal upwelling
- The Agulhas Current is the warm current of the south-west Indian Ocean and is known for the Agulhas retroflection, where it doubles back on itself south of Africa
- The warm Brazil Current meets the cold Falkland (Malvinas) Current off Argentina at the Brazil–Malvinas Confluence, producing one of the sharpest sea-surface temperature fronts in the world ocean
- Upwelling along the Humboldt Current supports one of the world's largest fisheries, and it is the weakening of that upwelling during an El Niño event that collapses the catch
- Cold currents lie offshore of the world's great coastal deserts — the Atacama, the Namib and the western Sahara — because cold water suppresses evaporation and stabilises the overlying air
The question asks which are NOT cold, so the highlighted rows are the answer: 1 and 2. Place the current on the map first — east coast of a continent means a warm western boundary current, west coast means a cold eastern boundary current — and the temperature follows without memorisation.
- The negation. The question asks which are NOT cold; option (c) prints exactly the two currents that ARE cold, and it will collect the marks of everyone who read the names correctly and the question carelessly
- Assuming that a current in the tropics must be warm and one in high latitudes cold. Temperature here is about direction of flow relative to the equator, not about where the name sounds like it belongs — the Humboldt runs along a tropical coast and is cold
- Confusing the Brazil Current with the Falkland (Malvinas) Current, which lies immediately to its south, flows the other way and is cold
UPPSC asks currents as one-line identifications — which current belongs to which ocean, which pairing is wrong, which of these is cold — and it very often wraps the question in a NOT. UPSC prefers to test the consequences rather than the labels: why a desert belt forms beside a particular coast, what an isothermal map in January is showing, or how currents redistribute the Earth's heat.
What could be the main reason/reasons for the formation of African and Eurasian desert belt? 1. It is located in the sub-tropical high pressure cells. 2. It is under the influence of warm ocean currents. Which of the statements given above is/are correct in this context?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(a) 1 only
Turns on exactly the warm-versus-cold distinction this question tests. Its second statement fails because the coasts concerned are washed by cold currents such as the Canary and Benguela, not warm ones — the same eastern-boundary rule that makes the Humboldt and California currents cold here.
Which of the following is/are correct inference/inferences from isothermal maps in the month of January? 1. The isotherms deviate to the north over the ocean and to the south over the continent. 2. The presence of cold ocean currents, Gulf Stream and North Atlantic Drift make the North Atlantic Ocean colder and the isotherms bend towards the north. Select the answer using the code given below:
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(a) 1 only
UPSC's version of the same trap, run in reverse. Its second statement is planted by calling the Gulf Stream and the North Atlantic Drift cold when they are warm western-boundary and drift currents — the mirror image of a paper asking you to spot which named currents are not cold.
Consider the following statements: 1. Ocean currents are the slow surface movement of water in the ocean. 2. Ocean currents assist in maintaining the Earth’s heat balance. 3. Ocean currents are set in motion primarily by prevailing winds. 4. Ocean currents are affected by the configuration of the ocean floor. Which of these statements are correct?
- (a) 1 and 2
- (b) 2, 3 and 4
- (c) 1, 3 and 4
- (d) 1, 2, 3 and 4
Answer(d) 1, 2, 3 and 4
Supplies the mechanism behind the labels. Because prevailing winds set the surface currents in motion and the resulting gyres carry warm water polewards and cold water equatorwards, a current's temperature is a consequence of where it sits in the circulation — which is why the boundary rule works at all.
Which of the following ocean currents is associated with Indian Ocean ?
- (a) Florida current
- (b) Canary current
- (c) Agulhas current
- (d) Kurile current
Answer(c) Agulhas current
The same commission asking about the same current five years earlier, this time by ocean rather than by temperature. Locating the Agulhas in the south-west Indian Ocean, along the east coast of southern Africa, is what tells you it is a warm western boundary current and therefore belongs in the answer here.
Which of the following statement is true?
- (a) Tide comes on the earth every day after exactly 12 hours 30 minutes.
- (b) Benguela current is a cold current of the pacific ocean.
- (c) Ocean salinity is maximum at the Tropic of Cancer and Capricorn.
- (d) If the sun, the earth and the moon are in a straight line then this situation is the situation of small tide.
Answer(c) Ocean salinity is maximum at the Tropic of Cancer and Capricorn.
Its second option is a cold-current statement bent by one word: the Benguela is indeed cold, but it belongs to the Atlantic and not the Pacific. UPPSC clearly likes testing whether a candidate can hold both attributes of a current — its temperature and its ocean — in mind at once, which is precisely the demand of the present question.
- practice — not a real PYQ
Which one of the following pairs of currents is correctly matched with its character?
- (a)Benguela Current — warm current of the South Atlantic
- (b)Kuroshio Current — cold current of the North Pacific
- (c)Agulhas Current — warm current of the Indian Ocean
- (d)Canary Current — warm current of the North Atlantic
Answer(c) Agulhas Current — warm current of the Indian Ocean. It is a western boundary current flowing polewards along south-east Africa. Benguela and Canary are cold eastern boundary currents, and the Kuroshio is a warm western boundary current.
- practice — not a real PYQ
The aridity of the Atacama and Namib deserts is attributed, among other causes, to
- (a)warm western boundary currents flowing along their coasts
- (b)cold eastern boundary currents flowing along their coasts
- (c)the absence of any ocean current in the adjoining waters
- (d)the seasonal reversal of currents in the adjoining ocean
Answer(b) cold eastern boundary currents flowing along their coasts — the Humboldt beside the Atacama and the Benguela beside the Namib. Cold water suppresses evaporation and stabilises the air above it, so moisture condenses as coastal fog rather than falling as rain.