Question 1

Which factor, along with low pressure, is important in tropical cyclone formation over warm oceans?

Accepted Answer

High evaporation from a warm sea surface and the supply of latent heat Tropical cyclones need a sufficiently warm ocean, generally about 26.5°C or more over a considerable depth, to provide abundant evaporation. Moist air rises around the low-pressure centre, and condensation releases latent heat, which increases buoyancy and can further lower pressure. Coriolis force and weak vertical wind shear are also important, but among the given choices warm-ocean moisture and latent-heat supply is the correct factor.

Question 2

Why is the polar front important in general circulation?

Accepted Answer

Because it is the meeting zone of cold polar and warmer mid-latitude air The polar front is a broad boundary where cold, dense polar air meets warmer air from the mid-latitudes. The strong horizontal temperature contrast, or baroclinic zone, provides energy for the development of mid-latitude cyclones and associated fronts. These cyclones transport heat poleward and help maintain the general circulation. Thus, the polar front is important not merely as a meeting line but as a zone of active weather and energy exchange.

Question 3

High thin clouds before a warm front may mark the beginning of which sequence?

Accepted Answer

Gradual cloud increase from cirrus to layered clouds As a warm front approaches, high cirrus clouds may appear first, followed by progressively lower and thicker clouds such as cirrostratus, altostratus, and nimbostratus. This gradual cloud thickening often precedes widespread, steady precipitation. Therefore, option A correctly describes the typical warm-front sequence.

Question 4

Under which condition is a region most suitable as a source region for air-mass formation?

Accepted Answer

Extensive uniform surface and stagnant air A source region is an extensive area where air remains over the surface long enough to acquire its temperature and moisture characteristics. Broad, uniform surfaces such as large oceans, deserts, snowfields, or plains are most suitable, especially when winds are light and conditions are stable. Hence option A is correct.

Question 5

If a maritime tropical air mass moves over a colder land surface, what is the most likely change?

Accepted Answer

The lower layer may cool and form fog or stratus cloud Maritime tropical air contains abundant moisture. When it travels over a colder land surface, the air near the ground is cooled from below and may reach saturation. Condensation can then produce advection fog or low stratus clouds. The air does not instantly lose all moisture, and pressure does not become uniform, so option A is correct.

Question 6

Which is the usual characteristic of a continental polar air mass?

Accepted Answer

Cold and dry A continental polar air mass develops over high-latitude land surfaces, where temperatures are low and evaporation is limited. Because it forms over land rather than an ocean, it normally contains little water vapour. Its usual properties are therefore cold temperature and low moisture, making option A the correct answer.

Question 7

Why can instability increase when a maritime polar air mass moves over a relatively warmer sea?

Accepted Answer

Due to heat and moisture supplied from below A maritime polar air mass is initially cold, while the warmer sea supplies sensible heat and moisture to its lowest layers. This creates a steep temperature decrease with height, making the lower atmosphere more buoyant and encouraging convection. Rising moist air can form showers and turbulent clouds, so option A is correct.

Question 8

Which statement best defines a front?

Accepted Answer

Transition zone between two different air masses A front is a relatively narrow transition zone between two air masses with contrasting properties, especially temperature and humidity. The boundary is not necessarily a single sharp line; it has width and may be associated with lifting, cloud development, precipitation, and changes in wind or pressure. Therefore option A is correct.

Question 9

Which cloud sequence may commonly appear before the arrival of a warm front?

Accepted Answer

Cirrus toward nimbostratus A warm front usually has a gentle slope, so warm air rises gradually over retreating colder air. Cloud development commonly begins with high cirrus and may progress through cirrostratus and altostratus to nimbostratus. This layered sequence often produces widespread, prolonged light or moderate precipitation, making option A correct.

Question 10

Why can weather remain unsettled for several days along a stationary front?

Accepted Answer

The front has very little horizontal movement A stationary front forms when neither adjoining air mass advances enough to displace the other. Since the boundary remains near the same location, lifting, cloud formation, and intermittent precipitation can continue over that area for a prolonged period. Thus the persistence of unsettled weather is best explained by very little horizontal movement, making option A correct.

Question 11

What is the general weather effect during frontolysis?

Accepted Answer

The front weakens and weather intensity decreases Frontolysis is the weakening or dissipation of a front. It generally occurs when the temperature and moisture contrast between the adjoining air masses decreases, or when the boundary loses its organized structure. With weaker contrast, uplift and frontal cloud or precipitation activity commonly decline. Therefore option A is correct.

Question 12

According to wave cyclone theory, an initial cyclonic wave forms due to what?

Accepted Answer

A disturbance along the polar front Wave cyclone theory begins with a disturbance or meander along the polar front. This disturbance bends the boundary between contrasting cold and warm air masses, producing a developing low-pressure wave. The wave can then intensify as air converges, rises, and the warm and cold fronts evolve. Ocean tides, stopped rotation, or total absence of moisture do not provide the basic explanation. Therefore, option A is correct.

Question 13

In the life cycle of a mid-latitude cyclone, what does occlusion indicate?

Accepted Answer

Weakening after maturity Occlusion occurs when the faster-moving cold front catches the warm front and lifts the warm air away from the surface. The warm sector is then cut off, reducing the cyclone’s supply of near-surface temperature contrast and energy. Occlusion usually marks a mature or late stage, after which the mid-latitude cyclone tends to weaken. Hence, option A is correct.

Question 14

What is a characteristic of the eye of a tropical cyclone?

Accepted Answer

A calm or relatively calm low-pressure centre The eye is the relatively calm central region of a mature tropical cyclone and has the lowest pressure near the storm centre. Air may slowly descend there, reducing cloud and rainfall temporarily. However, the surrounding eyewall contains the strongest winds and heaviest rain, so the calm eye should not be confused with the dangerous eyewall.

Question 15

Why is the eyewall of a tropical cyclone considered the most dangerous zone?

Accepted Answer

It has the strongest winds and intense rainfall The eyewall is the ring of deep, rapidly rising thunderstorm clouds surrounding the eye. It contains the cyclone’s strongest sustained winds, powerful gusts, intense rainfall, and sometimes tornadoes. The eye itself may be comparatively calm, but crossing into the eyewall produces the most severe wind and rain hazards.

Question 16

Why can a tropical cyclone weaken under strong vertical wind shear?

Accepted Answer

The upper and lower circulation structures become displaced Vertical wind shear means that wind speed or direction changes substantially with height. Strong shear tilts and displaces the cyclone’s upper circulation relative to its low-level centre, carries heat and moisture away, and disrupts the organised eyewall. This weakens the storm’s ability to maintain rising motion and central pressure.

Question 17

Why does a cyclone often weaken after landfall?

Accepted Answer

It loses the energy supply of the warm, moist sea surface A tropical cyclone is sustained by evaporation from a warm ocean and the release of latent heat when moist air rises and condenses. After landfall, this oceanic moisture and heat source is cut off. Surface friction over land also increases, slowing the circulation and disrupting the organised storm structure, although rainfall may continue for some time.

Question 18

Very closely spaced isobars near a cyclone centre indicate what?

Accepted Answer

A steep pressure gradient and strong winds Isobars join places with equal atmospheric pressure. When they are packed closely together, pressure changes rapidly over a short horizontal distance, producing a steep pressure gradient. Air accelerates in response to this gradient, so closely spaced isobars around a cyclone usually indicate strong or potentially damaging winds, subject to friction and the Coriolis effect.

Question 19

What is a major difference between mid-latitude and tropical cyclones?

Accepted Answer

Mid-latitude cyclones are frontal, whereas tropical cyclones are generally non-frontal Mid-latitude cyclones usually develop along the polar front, where contrasting warm and cold air masses meet and form fronts. Tropical cyclones generally develop over sufficiently warm tropical oceans and are warm-core, non-frontal systems driven by deep convection and latent-heat release. Both are low-pressure systems, but their origins and structures differ.

Question 20

Why is a tropical cyclone called a warm-core system?

Accepted Answer

Because latent heat released by condensation keeps the upper core warm A tropical cyclone is warm-core because its central troposphere is warmer than the surrounding atmosphere at comparable levels. Moist air rises in deep thunderstorms, and condensation releases latent heat, warming the storm column. This warming lowers the central pressure aloft and helps maintain the pressure field and circulation of the cyclone.

Question 21

Why is the slope of a cold front considered steeper than that of a warm front?

Accepted Answer

Dense cold air rapidly undercuts warm air Cold air is denser than warm air. At a cold front, the advancing cold air wedges underneath the warm air and lifts it comparatively abruptly, producing a relatively steep frontal surface. A warm front advances more gently because the lighter warm air rises gradually over retreating cold air, so its frontal slope is generally gentler.

Question 22

Why can low pressure intensify in a mid-latitude cyclone?

Accepted Answer

Upper-level divergence helps remove air from the surface column A mid-latitude cyclone can deepen when divergence occurs near the top of the troposphere. More air leaves the atmospheric column aloft than enters it, reducing the mass of air above the surface and lowering surface pressure. The resulting pressure gradient strengthens the circulation and may further intensify the cyclone through positive feedback.

Question 23

Why is high humidity helpful in the formation of a tropical cyclone?

Accepted Answer

It increases condensation and the supply of latent heat Humid air contains abundant water vapour. As moist air rises in a developing tropical disturbance, the vapour condenses into cloud droplets and releases latent heat. This heat warms the surrounding air, strengthens buoyant ascent, lowers central pressure, and helps maintain the cyclone’s heat engine. Humidity alone is not sufficient, because warm water, rotation, and weak vertical wind shear are also important.

Question 24

Why does the cold front usually move faster than the warm front in a mid-latitude cyclone?

Accepted Answer

Dense cold air advances beneath and lifts warm air more forcefully Cold air is denser than warm air and tends to advance as a wedge beneath the warm air. Its boundary is usually steeper, and the associated pressure gradient and winds commonly make it move faster than the gently sloping warm front. It can therefore overtake the warm front and produce occlusion, so option A is correct.

Question 25

Why does pressure decrease toward the centre of a tropical cyclone?

Accepted Answer

Strong low-level convergence and rising air help maintain a central low-pressure area In a tropical cyclone, surface winds spiral inward because of the pressure gradient and converge toward the centre. Air is then forced upward in powerful convection. This removal of mass from the central column, together with upper-level outflow, supports very low pressure at the centre. Hence option A is correct.

Air masses, fronts, and cyclones

Practice questions

01 Which factor, along with low pressure, is important in tropical cyclone formation over warm oceans?

02 Why is the polar front important in general circulation?

03 High thin clouds before a warm front may mark the beginning of which sequence?

04 Under which condition is a region most suitable as a source region for air-mass formation?

05 If a maritime tropical air mass moves over a colder land surface, what is the most likely change?

06 Which is the usual characteristic of a continental polar air mass?

07 Why can instability increase when a maritime polar air mass moves over a relatively warmer sea?

08 Which statement best defines a front?

09 Which cloud sequence may commonly appear before the arrival of a warm front?

10 Why can weather remain unsettled for several days along a stationary front?

11 What is the general weather effect during frontolysis?

12 According to wave cyclone theory, an initial cyclonic wave forms due to what?

13 In the life cycle of a mid-latitude cyclone, what does occlusion indicate?

14 What is a characteristic of the eye of a tropical cyclone?

15 Why is the eyewall of a tropical cyclone considered the most dangerous zone?

16 Why can a tropical cyclone weaken under strong vertical wind shear?

17 Why does a cyclone often weaken after landfall?

18 Very closely spaced isobars near a cyclone centre indicate what?

19 What is a major difference between mid-latitude and tropical cyclones?

20 Why is a tropical cyclone called a warm-core system?

21 Why is the slope of a cold front considered steeper than that of a warm front?

22 Why can low pressure intensify in a mid-latitude cyclone?

23 Why is high humidity helpful in the formation of a tropical cyclone?

24 Why does the cold front usually move faster than the warm front in a mid-latitude cyclone?

25 Why does pressure decrease toward the centre of a tropical cyclone?

Was this question useful?

Student Reviews

Add Muft Shiksha to your Home Screen