CDS (I) 2020 General Knowledge · Question 37 of 120

Correct — B, Bora. The bora is a northerly to north-easterly katabatic wind of the Adriatic — cold, dry and violently gusty, pouring down the Dinaric ranges onto the coasts of Slovenia, Croatia and Montenegro and onto Trieste. Cold dense air ponds over the snow-covered plateaus behind the coast; when it spills over the ridge it warms as it descends, but it starts so cold that it still arrives at sea level as a cold wind. That is the detail the stem is pointing at. Bora gusts have been clocked above 220 km/h, with 248 km/h recorded at the Maslenica Bridge near Zadar, and the wind is commonest in winter.

• (a)Mistral — Also a cold downslope wind of the Mediterranean, but on the wrong side of Italy — the mistral funnels down the Rhone valley in southern France and out over the Gulf of Lion, not the Adriatic.
• (c)Bise — A cold, dry north-easterly of Switzerland and eastern France, felt around the Swiss plateau and Lake Geneva. It has the right temperature and the wrong continent-corner, and it is not a mountain-descent wind of the Adriatic shore.
• (d)Blizzard — Not a named regional wind at all. A blizzard is a weather event — a snowstorm with strong wind and low visibility — and the word is used of high latitudes generally rather than of one coast.

Katabatic winds are gravity winds: dense cold air formed over high ground drains downslope under its own weight. Descending air warms adiabatically, so whether such a wind feels warm or cold depends on how cold it was to begin with. The bora and the mistral start over snow or cold plateau and reach the lowlands cold; the chinook of the Rockies and the foehn of the Alps start much warmer and arrive hot and dry.

Local-wind questions are almost always solved by pairing a name to a place, so build the list geographically rather than alphabetically. Bora on the eastern Adriatic; mistral in the Rhone valley and the Gulf of Lion; sirocco and khamsin blowing north off the Sahara; harmattan west across the Sahel; bise on the Swiss plateau; loo across the north Indian plains in May and June. The one distractor that is not a wind name at all — blizzard — can be discarded before you start.

• The bora is a northerly to north-easterly katabatic wind of the areas near the Adriatic Sea.
• It is cold on arrival: its air is so cold at source that warming on descent does not offset it.
• It blows on the coasts of Croatia, Slovenia and Montenegro and at Trieste, and is also felt near Novorossiysk on the Black Sea.
• Gusts of 248 km/h have been recorded at the Maslenica Bridge near Zadar.
• The mistral is the comparable cold descent wind of the Rhone valley, and the bise a cold dry north-easterly of Switzerland and eastern France.

• Assuming every descending wind is warm; the bora and the mistral are cold at the bottom of the slope.
• Placing the mistral on the Adriatic — it belongs to southern France and the Gulf of Lion.

As a wind-to-region match, or as an odd-one-out on which named wind is cold, warm, or not tied to a given sea.

• practice — not a real PYQ

  The mistral, a cold and dry wind, is associated with which one of the following regions?

  • (a)The Rhone valley and the Gulf of Lion
  • (b)The eastern Adriatic coast
  • (c)The Sahel and West Africa
  • (d)The north Indian plains

  Answer(a) The Rhone valley and the Gulf of Lion — the mistral funnels down the Rhone in southern France and blows out over the Mediterranean.

• practice — not a real PYQ

  Which one of the following is a warm and dry downslope wind?

  • (a)Bora
  • (b)Mistral
  • (c)Chinook
  • (d)Bise

  Answer(c) Chinook — it descends the eastern slopes of the Rockies warm and dry, and can strip snow cover fast enough to earn the name snow-eater.