Local Winds, Air Masses & Fronts – NDA Geography PYQs

NDA 2016-I

Q. 1. What is a stationary front?

(a) A front that is moving very slowly

(b) A front that is permanently fixed in one location

(c) A front between two air masses of identical properties

(d) A front that is not moving

Answer: (d) A front that is not moving

Explanation: A stationary front is a front that is not moving: the boundary between two air masses (warm and cold) where neither air mass is advancing or retreating. This can occur when the temperature and pressure gradient between the two air masses is insufficient to cause movement. Stationary fronts can persist for days, bringing prolonged cloudy, rainy, or foggy conditions to the region below. They are also called quasi-stationary fronts. They differ from slow-moving fronts (option a): a truly stationary front has no movement. Concept Tested: Stationary front: boundary between warm and cold air masses that is NOT moving; prolonged cloudy/rainy conditions

NDA 2015-II

Q. 2. Consider the following statements regarding cold fronts:

1. Cold front occurs when cold air replaces warm air.

2. Cold fronts usually move faster than warm fronts.

3. Cold fronts typically move slower than warm fronts.

Which of the statements given above is/are correct?

(a) 1 and 3 only

(b) 1 and 2 only

(c) 2 and 3 only

(d) 1, 2 and 3

Answer: (b) 1 and 2 only

Explanation: Statement 1: Correct. A cold front is defined as the boundary where cold air is advancing and replacing warm air. The cold, denser air slides beneath the lighter warm air, lifting it upward and producing clouds and precipitation. Statement 2: Correct. Cold fronts typically move 20–35 mph and move faster than warm fronts (which move at 10–25 mph). This is why cold fronts eventually catch up with warm fronts, forming occluded fronts. Statement 3: Incorrect. Statement 3 contradicts Statement 2. Cold fronts move FASTER than warm fronts: not slower. Concept Tested: Cold fronts: cold air replaces warm; move FASTER than warm fronts; leads to occluded fronts eventually

NDA 2014-I

Q. 3. An occluded front is formed when:

(a) Cold and warm fronts intersect at a point

(b) Two cold fronts merge

(c) A cold front overtakes a warm front

(d) Two warm fronts merge

Answer: (c) A cold front overtakes a warm front

Explanation: An occluded front forms when a cold front (which moves faster) catches up with a warm front. As the cold front overtakes the warm front, the warm air between them is lifted completely off the surface. The term “occluded” means “cut off”: the warm air sector is cut off from the surface. There are two types: Cold occlusion: the advancing cold air is colder than the cold air ahead of the warm front. Warm occlusion: the advancing cold air is less cold than the cold air ahead of the warm front. Concept Tested: Occluded front: cold front catches up with and overtakes warm front; warm air is lifted off the surface

NDA 2013-II

Q. 4. Which of the following statements about air masses are correct?

1. Maritime Tropical (mT) air mass is warm and moist.

2. Continental Polar (cP) air mass is cold and dry.

3. Maritime Polar (mP) air mass is cold and moist.

Select the correct answer using the code given below:

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Answer: (d) 1, 2 and 3

Explanation: All three statements are correct: Statement 1: Maritime Tropical (mT): forms over tropical oceans → warm (tropical) + moist (maritime). Statement 2: Continental Polar (cP): forms over polar land masses → cold (polar) + dry (continental). Statement 3: Maritime Polar (mP): forms over polar oceans → cold (polar) + moist (maritime). The air mass classification system consistently works: “maritime” = moist; “continental” = dry; “tropical” = warm; “polar” = cold. Concept Tested: Air mass properties: mT (warm+moist), cP (cold+dry), mP (cold+moist); all three correct

NDA 2012-II

Q. 5. Which type of air mass is described as hot and dry?

(a) Maritime Tropical

(b) Maritime Polar

(c) Continental Tropical

(d) Continental Polar

Answer: (c) Continental Tropical

Explanation: Air masses are classified by two characteristics: 1. Source region temperature: Tropical (T) = warm/hot; Polar (P) = cold. 2. Source region moisture: Continental (c) = dry; Maritime (m) = moist. Combinations: cT (Continental Tropical): hot and DRY. Forms over tropical deserts (Sahara, Arabian Desert). Correct ✓. mT (Maritime Tropical): warm and MOIST. Forms over tropical oceans. cP (Continental Polar): cold and DRY. Forms over polar landmasses. mP (Maritime Polar): cold and MOIST. Forms over polar oceans. Concept Tested: Continental Tropical (cT) air mass: hot and dry; forms over tropical deserts; air mass classification

NDA 2011-II

Q. 6. Which of the following best describes an air mass?

(a) A layer of air in the upper atmosphere

(b) A large body of air with nearly uniform temperature and humidity throughout

(c) The area of the earth covered by air

(d) The mass of atmospheric air above a given point

Answer: (b) A large body of air with nearly uniform temperature and humidity throughout

Explanation: An air mass is a large volume of air: covering hundreds of thousands of square kilometres: in which temperature and humidity are relatively uniform both horizontally and vertically. Air masses form over source regions (flat, extensive areas with uniform surface characteristics) where air remains stationary for days or weeks, acquiring the temperature and humidity of the underlying surface. When an air mass moves away from its source region and meets another air mass with different properties, a front forms at the boundary. Concept Tested: Air mass: large body of air with uniform temperature and humidity; forms over source regions

NDA 2009-II

Q. 7. ‘Bora’ is a type of:

(a) Hot and moist wind

(b) Hot and dry wind

(c) Cold and moist wind

(d) Cold and dry wind

Answer: (d) Cold and dry wind

Explanation: The Bora is a cold, dry, gusty, northeasterly wind that blows from the Dinaric Alps (inland Balkans) toward the Adriatic Sea coast (Croatia, Slovenia, Montenegro). It originates as cold, dense air from the continental interior of eastern Europe that flows down the mountain slopes toward the coast. The Bora can be dangerously strong (up to 200+ km/h in gusts) and brings a sudden temperature drop to the coastal Adriatic region. Concept Tested: Bora: cold, dry, gusty wind blowing from Dinaric Alps toward the Adriatic coast in southeast Europe

★ JOVIK Exam Insight Local winds classification for NDA: HOT/WARM local winds: Sirocco (Sahara→Mediterranean), Chinook (Rocky Mtns, N. America), Foehn (Alps, Europe), Khamsin (Egypt), Zonda (Andes, Argentina), Santa Ana (California). COLD local winds: Bora (Adriatic coast), Mistral (Rhône Valley, France), Blizzard (North America), Purga (Siberia), Pampero (Argentina). NDA has tested Sirocco (2007-II), Foehn (2008-II), Chinook (2009-I), Bora (2009-II), and Mistral (in Ch. 14). All five are important.

NDA 2009-I

Q. 8. The Chinook is a local wind associated with:

(a) The Alps in Europe

(b) The Rocky Mountains in North America

(c) The Andes in South America

(d) The Himalayas in Asia

Answer: (b) The Rocky Mountains in North America

Explanation: The Chinook is a warm, dry wind that blows down the eastern (leeward) side of the Rocky Mountains in western Canada and northwestern USA. Like the Foehn, it is formed by the thermodynamic warming of descending air. Its name comes from the Chinook indigenous people of the Pacific coast. The Chinook can raise temperatures rapidly (5–10°C in minutes) and is known as the “snow eater” because it rapidly melts snow. The equivalent in the Alps is the Foehn; in the Andes, it is the Zonda. Concept Tested: Chinook: warm dry wind on eastern (leeward) side of Rocky Mountains; “snow eater”; North America

NDA 2008-II

Q. 9. Foehn is a wind of:

(a) United Kingdom

(b) USA

(c) Alps

(d) Himalayas

Answer: (c) Alps

Explanation: The Foehn (pronounced “fern”) is a warm, dry wind that blows down the leeward (northern) side of the Alps in Switzerland, Austria, and Germany. When moist air from the Mediterranean or Atlantic rises over the Alps: 1. It cools at the Saturated Adiabatic Lapse Rate (~5°C/km) on the windward side (precipitation forms). 2. It descends the leeward side warming at the Dry Adiabatic Lapse Rate (~10°C/km). 3. The net effect is warm, dry air at the base: the Foehn effect. The Foehn can raise temperatures dramatically (up to 20°C in hours) and melt snow rapidly, sometimes causing avalanches and floods. Concept Tested: Foehn: warm dry wind on leeward side of the Alps; thermodynamic warming as air descends

NDA 2007-II

Q. 10. Sirocco is a:

(a) Hot and dry or hot and moist wind blowing from Sahara towards Mediterranean

(b) Cold wind of Asia

(c) Hot wind of the southern USA

(d) Cold wind of Canada

Answer: (a) Hot and dry or hot and moist wind blowing from Sahara towards Mediterranean

Explanation: The Sirocco (also spelled Scirocco) is a hot, dry wind that originates over the Sahara Desert in North Africa and blows northward across the Mediterranean Sea toward southern Europe. As it blows over the Mediterranean, it picks up moisture and may arrive in southern Europe (especially Sicily, Malta, and southern Italy) as a hot, humid wind. The Sirocco is associated with dusty conditions, oppressive heat, and sometimes coloured (red) dust deposits. Concept Tested: Sirocco: hot wind from Sahara; blows northward across Mediterranean to southern Europe

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