Consider the following statements about Roaring Forties : 1. They are strong Westerly winds found in the oceans of Southern Hemisphere. 2. The strong east to west air currents are caused by the combination of air being displaced from the Equator towards the South Pole and the earth’s rotation and abundance of landmasses to serve as wind breaks. Which of the statements given above is/are correct ?
- (a)1 only
- (b)2 only
- (c)Both 1 and 2
- (d)Neither 1 nor 2
Correct — A, 1 only. Statement 1 is a plain description of the belt and is right: the Roaring Forties are the strong westerlies that sweep the Southern Ocean roughly between 40° S and 50° S, and they are a Southern Hemisphere phenomenon because that is where the wind belt runs almost entirely over water. Statement 2 is the same textbook sentence with two words switched, and both switches make it false. The air currents run west to east, not east to west — that is what makes them westerlies in the first place. And their ferocity comes from the near-total ABSENCE of landmasses at those latitudes, not from an abundance of them; with no continent to drag on the flow, the wind keeps its speed all the way round the globe. So only statement 1 survives.
- (b)2 only — Statement 2 fails twice over — on the direction of flow and on the role of land. A statement that is wrong on both of its causal claims cannot be the only correct one.
- (c)Both 1 and 2 — This is the trap the examiner built. Statement 2 sounds authoritative because most of it — displacement of air from the Equator towards the pole, plus the earth's rotation — is genuinely part of the explanation. A candidate who reads for the familiar phrases and not for the two altered words picks this.
- (d)Neither 1 nor 2 — Statement 1 is straightforwardly correct, so a blanket rejection is wrong. The Roaring Forties are indeed strong westerlies of the Southern Hemisphere oceans.
Between about 30° and 60° latitude in each hemisphere, air moving polewards from the subtropical high is deflected by the earth's rotation into a wind that blows from the west. These are the westerlies. In the Northern Hemisphere the belt is repeatedly interrupted by North America and Eurasia, so the flow is broken and variable. In the Southern Hemisphere the same latitudes are almost pure ocean — only the southern tip of South America, and New Zealand, stand in the way — so the westerlies blow with a strength and constancy that sailors named after the degrees of latitude: the Roaring Forties, the Furious Fifties and the Screaming Sixties.
The way to crack a two-statement item like this is to compare it word by word with the sentence it was built from, because examiners very often lift a standard explainer and alter one or two words. Here the source sentence describes 'west-to-east air currents' intensified by 'the lack of landmasses to serve as windbreaks'; the paper prints 'east to west' and 'abundance of landmasses'. Change either word and the statement dies. There is also a simple internal check available with no outside knowledge at all: statement 1 calls these winds Westerly, and statement 2 then calls them east-to-west currents. A wind named for the west blows FROM the west, so the two statements contradict each other, and both cannot stand. That alone rules out option (c). Note also the shortcut to statement 2's second error — the reason the Southern Hemisphere westerlies are stronger is precisely that there is so little land there, a point UPSC itself set as a prelims question in 2011.
- The Roaring Forties are strong westerly winds of the Southern Ocean, running roughly between 40° S and 50° S.
- They flow from west to east; a wind is named for the direction it comes from.
- Their strength comes from the near-absence of land at those latitudes, which leaves nothing to slow the flow.
- The stronger belts further south carry the sailors' names Furious Fifties and Screaming Sixties.
- The same westerly belt exists in the Northern Hemisphere but is broken up by North America and Eurasia.
Two altered words are the whole question; everything else in statement 2 is standard textbook material.
- Reading a wind's name as the direction it blows towards; a westerly comes from the west.
- Accepting a long statement because most of it is familiar, without checking every clause.
- Assuming land makes winds stronger by funnelling them, when at these latitudes land is what breaks them up.
NDA and UPSC both set the wind belts as two-statement or match-the-list items, and almost always plant the error in the direction of flow or the cause of the wind's strength.
Consider the following statements about the “Roaring Forties”: I. They blow uninterrupted in the Northern and Southern Hemispheres. II. They blow with great strength and constancy. III. Their direction is generally from North-West to East in the Southern Hemisphere. IV. Overcast skies, rain and raw weather are generally associated with them. Which of these statements are correct?
- (a) I, II and III
- (b) II, III and IV
- (c) I, III and IV
- (d) I, II and IV
Answer(b) II, III and IV
The same belt, tested eighteen years earlier, and the key confirms both points the NDA item turns on — the flow is towards the east, and the Roaring Forties are a Southern Hemisphere feature only.
Westerlies in southern hemisphere are stronger and persistent than in northern hemisphere. Why? 1. Southern hemisphere has less landmass as compared to northern hemisphere. 2. Coriolis force is higher in southern hemisphere as compared to northern hemisphere Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(a) 1 only
UPSC marked 'less landmass' as the correct reason for the strength of these winds — the exact opposite of what statement 2 of this NDA item claims, which is why that statement is false.
Which of the following statements concerning Mediterranean climatic region are correct ? 1. It is found in the latitude range 30° to 45° northern and southern hemisphere 2. Mediterranean climate experiences extreme temperature conditions 3. In Mediterranean climate, rainfall occurs mainly during summer season 4. In Mediterranean climate, rainfall is mainly due to Westerlies Select the correct answer using the code given below :
- (a) 1, 2 and 4
- (b) 1 and 4 only
- (c) 1, 2 and 3
- (d) 3 and 4
Answer(b) 1 and 4 only
The same wind belt seen from the land side: where the westerlies do reach a continent, they deliver winter rain. A useful pair with this item, which is about what those winds do where there is no land at all.
- practice — not a real PYQ
The Southern Hemisphere westerlies are stronger and steadier than their Northern Hemisphere counterparts mainly because
- (a)the Coriolis force is larger in the Southern Hemisphere
- (b)there is very little land at those latitudes in the Southern Hemisphere
- (c)the Southern Hemisphere receives more solar energy
- (d)the Antarctic ice sheet cools the air and speeds it up
Answer(b) there is very little land at those latitudes in the Southern Hemisphere — with no continents to create friction, the flow keeps its speed all the way round.
- practice — not a real PYQ
The names Roaring Forties, Furious Fifties and Screaming Sixties refer to
- (a)tropical cyclones of the western Pacific
- (b)cold ocean currents off the west coast of South America
- (c)belts of strong westerly wind in the Southern Ocean
- (d)monsoon surges over the Bay of Bengal
Answer(c) belts of strong westerly wind in the Southern Ocean — named by sailors after the degrees of southern latitude in which each blows.