CDS (I) 2021 General Knowledge · Question 71 of 120

Correct — B, 3, 4, 2, 1. The four names in List I are regional labels for one and the same storm — a tropical cyclone — and each belongs to the ocean where it was coined. Cyclone is the Indian Ocean word, so A goes to 3. Hurricane belongs to the Atlantic and the eastern Pacific, giving B to 4. Typhoon is the western Pacific and South China Sea word, so C goes to 2. Willy-willy is the Australian term, which leaves D with 1, Western Australia. Reading across, A-3, B-4, C-2, D-1.

• (a)3, 2, 4, 1 — Gets the Indian Ocean and Western Australia rows right but swaps hurricanes and typhoons, sending hurricanes to the South China Sea. Hurricane is an Atlantic word borrowed from the Caribbean; it is not used in the western Pacific.
• (c)1, 4, 2, 3 — Begins by putting Indian Ocean cyclones in Western Australia and ends by putting willy-willies in the Indian Ocean, so the two easiest rows are both reversed.
• (d)1, 2, 4, 3 — Keeps the same wrong opening and closing as option (c) while also sending hurricanes to the South China Sea, which leaves no row correct.

Tropical cyclones form over warm ocean water, usually above about 26.5 degrees Celsius, away from the equator where the Coriolis effect can start the rotation. The physics is identical everywhere; only the vocabulary changes with the basin. Around India the storms are simply called cyclones, and the India Meteorological Department names them from a list contributed by thirteen countries of the north Indian Ocean region. The Atlantic and eastern Pacific use hurricane, from a Caribbean word; the western Pacific uses typhoon.

Match-lists of this kind are solved by anchoring the row you are certain of and letting the code table do the rest. Hurricane to Atlantic is the anchor for most candidates, and only option (b) puts 4 against B. Willy-willy is the odd term here and is worth remembering as Australian; the older Indian textbooks that this list follows treat it as the Australian name for a tropical cyclone, and UPSC used it in the same sense in 1995. The one thing to keep straight is that a tornado is not on this list at all — it is a small, short-lived land phenomenon and belongs to a different family altogether.

• Tropical cyclones need sea surface temperatures of roughly 26.5 degrees Celsius or more and enough distance from the equator for the Coriolis effect to act.
• The same storm is called a cyclone in the Indian Ocean, a hurricane in the Atlantic and eastern Pacific, a typhoon in the western Pacific and South China Sea, and a willy-willy in Australia.
• Cyclones in the northern hemisphere rotate anticlockwise; in the southern hemisphere they rotate clockwise.
• Names for north Indian Ocean cyclones come from a list contributed by thirteen member countries and are issued by the India Meteorological Department.
• The eye is the calm low-pressure core; the eyewall around it carries the strongest winds and heaviest rain.

• Treating hurricane, typhoon and cyclone as different kinds of storm rather than as regional names for the same one.
• Bringing tornadoes into the comparison; they are unrelated to this list.
• Assuming willy-willy belongs to Africa or to the Pacific islands rather than to Australia.

As a name-to-region match-list, or as a single-line item asking what a willy-willy or a typhoon is.

• practice — not a real PYQ

  Tropical cyclones of the western Pacific and the South China Sea are known by which one of the following names?

  • (a)Hurricane
  • (b)Typhoon
  • (c)Willy-willy
  • (d)Tornado

  Answer(b) Typhoon — hurricane belongs to the Atlantic and eastern Pacific, willy-willy to Australia.

• practice — not a real PYQ

  Tropical cyclones do not form along the equator mainly because of the absence of which one of the following?

  • (a)Warm ocean water
  • (b)Moisture in the air
  • (c)The Coriolis effect
  • (d)Low pressure

  Answer(c) The Coriolis effect — it vanishes at the equator, so an incipient storm cannot acquire the rotation it needs.