Match the following :
Region
(a) Sahara desert
(b) Greece
(c) Iran
(d) Alps
Name of the wind
(i) Foehn
(ii) Semun
(iii) Sirocco
(iv) Khamsin

Question

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Correct — option (2), which reads (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i). Take the securest row first. Statement (d), the Alps, goes with item (i), the Foehn, and this pairing alone settles the entire question, because no other choice offers it. The Foehn is the type example of a warm, dry downslope wind on the lee side of a mountain range: moist air off the Mediterranean is forced up the southern flank of the Alps, cools, and drops its moisture as rain on the windward slope; the latent heat released in that condensation stays in the air, so when the now-dry air descends the northern side and is compressed it arrives warmer than it began, capable of lifting temperatures by as much as fourteen degrees in a matter of hours, melting snow and drying pasture. The name itself is Alpine, from a Latin word for a mild westerly, and the same mechanism carries other names elsewhere — Chinook in the Rockies, Santa Ana in California, Zonda in Argentina, Nor'wester in New Zealand, Halny in the Carpathians. Statement (c), Iran, goes with item (ii), Semun, the wind more usually spelt Simoom and known also as samiel, from words meaning poison wind; it is a strong, hot, dry, dust-laden wind of the deserts of western Asia and North Africa, blowing across the Sahara, Jordan, Iraq, Syria, the Arabian Peninsula and the Iranian deserts, where temperatures can exceed fifty-four degrees Celsius and relative humidity fall below ten per cent. Statements (a) and (b) are two names for one air stream, and understanding that is the key to the pair. A hot dry mass rises off the Sahara or the Arabian desert and is drawn north across the Mediterranean; on the Egyptian shore it is called the Khamsin, from the Arabic for fifty, after the season in which it blows, and that is item (iv) beside the Sahara. By the time the same stream reaches the northern shore it has crossed the sea and picked up moisture, and there it is called the sirocco, sirokos in Greece and scirocco in Italy and Malta, which is item (iii) beside Greece. The pairing therefore follows the convention that a local wind is named by the shore that experiences it, and the two rows are consistent rather than contradictory.

Why the other options are wrong — (a) This choice gets the middle two rows right, giving the sirocco to Greece and the Semun to Iran, and then swaps the outer pair, putting the Foehn over the Sahara and the Khamsin over the Alps. Both halves of that swap are impossible. The Foehn requires a mountain barrier and a descending lee slope, and the Sahara is a low desert basin with no such range in the position needed; the Khamsin is by definition a wind of Egypt and the Saharan margin and has nothing to do with an Alpine valley. This is the choice that will catch a candidate who checks a couple of rows, finds them right and commits, and it is the reason the Alps row rather than the Greece row should be used as the anchor here.  (c) Every row of this choice is displaced. It puts the Foehn on the Sahara, the Semun in Greece, the Khamsin in Iran and the sirocco over the Alps. The row that gives the sirocco to the Alps is the most instructive failure, because the sirocco is defined by its passage across the Mediterranean and by the humidity and the reddish dust it deposits on the northern shore — the blood rain of Italian folklore — which places it on a coast rather than on a mountain lee. Reading each local wind as a statement about a specific geography, rather than as a name to be remembered in isolation, makes a permutation like this one visibly wrong at every line.  (d) This choice gives the Semun to the Sahara, the Khamsin to Greece, the Foehn to Iran and the sirocco to the Alps. The first row is the interesting one, because it is not absurd: the Simoom does blow across the Sahara as well as across the deserts of western Asia, so a candidate could defend it in isolation. That is precisely the danger of judging a matching question row by row instead of as a whole permutation. Once the other three rows are examined the choice collapses, since the Foehn cannot belong to Iran, which has no Alpine lee slope in the sense the wind requires, and the Khamsin is a wind of the African rather than the European shore.

Concept: Local winds are regional air movements produced by the interaction of pressure gradients with terrain and with the contrast between land and sea, and they are conventionally sorted into hot and cold. The hot group includes the Foehn of the Alps and its cousins the Chinook, the Santa Ana and the Zonda, all produced by adiabatic descent on a mountain's lee side; the Simoom, Khamsin, Sirocco, Harmattan and Loo, all produced by hot desert air moving outward; and the Brickfielder of Australia and the Norwester of New Zealand. The cold group includes the Mistral of the Rhone valley, the Bora of the Adriatic, the Blizzard, the Buran of central Asia, the Purga and the Pampero of Argentina. Two physical principles explain almost all of them. The first is adiabatic temperature change: air cools at about six and a half degrees per kilometre as it rises and warms at about ten degrees per kilometre as it descends dry, and the difference between those rates, caused by latent heat released during condensation, is why a Foehn arrives warmer than the air that started up the windward slope. The second is that air moving over a large water body gains moisture, which is why the same Saharan stream is dry as the Khamsin and humid as the sirocco.

State PCS 2021 Q18 — Geography PYQ with Answer

State PCS 2021 Q18 — Geography PYQ with Answer