World and Physical Geography

241. Hurricanes rarely form or move within 5 degrees of the equator,

Hurricanes rarely form or move within 5 degrees of the equator, because

[amp_mcq option1=”Coriolis effect is weakest here” option2=”Coriolis effect is strongest here” option3=”it has low pressure” option4=”it has high temperature” correct=”option1″]

This question was previously asked in
UPSC CAPF – 2012
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Hurricanes (tropical cyclones) require the Coriolis effect to initiate and maintain their rotation. The Coriolis effect is an apparent force caused by the Earth’s rotation, which deflects moving objects (like air and water) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This effect is zero at the equator and increases with latitude. For a tropical cyclone to form and rotate, the Coriolis effect must be strong enough to start the cyclonic circulation. Within 5 degrees of the equator, the Coriolis effect is too weak, preventing the necessary sustained rotation from developing, even if other conditions (warm water, unstable atmosphere, moisture) are present.
Tropical cyclones (hurricanes) require the Coriolis effect for rotation, and this effect is weakest near the equator (within approximately 5 degrees latitude).
Other conditions necessary for tropical cyclone formation include warm sea surface temperatures (typically above 26.5°C), sufficient atmospheric moisture, low vertical wind shear, and a pre-existing disturbance or low-pressure area. However, even if these conditions are met, the lack of sufficient Coriolis force near the equator inhibits formation.

242. Whenever a tropical cyclone moves to land, much of its severity is red

Whenever a tropical cyclone moves to land, much of its severity is reduced. This is because

  • 1. its source of moisture is cut off
  • 2. the friction over land kills tropical cyclones

Select the correct answer using the code given below.

[amp_mcq option1=”1 only” option2=”2 only” option3=”Both 1 and 2″ option4=”Neither 1 nor 2″ correct=”option3″]

This question was previously asked in
UPSC CAPF – 2012
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The correct answer is C) Both 1 and 2. When a tropical cyclone moves over land, both the cutting off of its moisture source and the increased friction contribute significantly to the reduction of its severity and eventual dissipation.
– Statement 1 is correct: Tropical cyclones draw immense energy from the latent heat released by the condensation of water vapor evaporated from the warm ocean surface. Moving over land cuts off this primary energy source.
– Statement 2 is correct: The land surface is much rougher than the ocean surface, causing increased friction. This friction slows down the winds, disrupts the storm’s circulation pattern, and contributes to its weakening. While friction might not “kill” it instantly, it plays a vital role in its decay along with the loss of moisture and sensible heat from the surface.
The rapid weakening of a tropical cyclone upon landfall is primarily due to the combined effect of losing access to the warm, moist ocean and the increased friction from the land surface. Other factors like interaction with topography and ingestion of drier air can also contribute to its weakening.

243. Relative humidity

Relative humidity

[amp_mcq option1=”increases with increased temperature” option2=”decreases with increased temperature” option3=”decreases with decreased temperature” option4=”has no relation with increase or decrease of temperature” correct=”option2″]

This question was previously asked in
UPSC CAPF – 2011
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Relative humidity decreases with increased temperature, assuming the absolute amount of water vapour in the air remains constant.
Relative humidity is defined as the ratio of the partial pressure of water vapour to the equilibrium vapour pressure of water at a given temperature. The equilibrium vapour pressure (the maximum amount of water vapour the air can hold) increases significantly with increasing temperature.
If the amount of water vapour in the air stays the same, but the temperature rises, the air’s capacity to hold water vapour increases. This means the actual vapour content becomes a smaller percentage of the maximum possible content, resulting in a decrease in relative humidity.

244. Tsunami causes devastation near the coast of the sea as the speed of t

Tsunami causes devastation near the coast of the sea as the speed of the sonic waves generated at the epicentre is

[amp_mcq option1=”directly proportional to the depth of the sea” option2=”inversely proportional to the depth of the sea” option3=”directly proportional to the distance between the coast and epicentre” option4=”inversely proportional to the distance between the coast and epicentre” correct=”option1″]

This question was previously asked in
UPSC CAPF – 2011
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The correct option is A) directly proportional to the depth of the sea.
The speed of a tsunami wave (a shallow-water wave in terms of wavelength relative to depth) is determined by the formula v = sqrt(g * d), where ‘v’ is speed, ‘g’ is the acceleration due to gravity, and ‘d’ is the depth of the water. This formula shows that the wave speed is directly proportional to the square root of the depth. Therefore, in deeper water, tsunamis travel faster, and as they approach the shallower coast, they slow down.
Although the relationship is precisely proportional to the square root of the depth, among the given options, “directly proportional to the depth of the sea” is the correct representation that speed increases with depth. In the open ocean, where the depth is great, tsunamis can travel at hundreds of kilometers per hour. Near the coast, the decrease in depth causes the wave to decelerate significantly, leading to the stacking up of energy and a dramatic increase in wave height as it breaks upon the shore.

245. Which one among the following local winds is not characteristically ho

Which one among the following local winds is not characteristically hot and dry ?

[amp_mcq option1=”Sirocco” option2=”Mistral” option3=”Khamsin” option4=”Chinook” correct=”option2″]

This question was previously asked in
UPSC CAPF – 2011
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Let’s examine the characteristics of each local wind:
A) Sirocco: A hot, dry wind originating in the Sahara Desert and blowing northward across the Mediterranean Sea. It picks up moisture over the sea but is initially hot and dry.
B) Mistral: A strong, cold, dry wind that blows from the north down the Rhône Valley in France towards the Mediterranean Sea. It is associated with high pressure and clear, cold weather.
C) Khamsin: A hot, dry, sandy wind blowing from the south over Egypt and the Middle East, typically occurring in spring. Similar in nature to Sirocco.
D) Chinook: A type of Foehn wind that occurs on the eastern side of the Rocky Mountains in North America. It is a warm, dry wind caused by air descending the leeward side of a mountain range.
Comparing these, Sirocco, Khamsin, and Chinook are all characteristically hot and dry. Mistral is characteristically cold and dry.
Local winds have distinct characteristics regarding temperature, moisture content, and origin. Identifying a wind that is *not* hot and dry among a list of predominantly hot and dry winds requires knowing the specific nature of each wind type.
Foehn winds like the Chinook are warm because the descending air is compressed and warms adiabatically after losing moisture on the windward side of the mountain. The Mistral, conversely, is a katabatic wind, associated with cold air flowing down from elevated, cold landmasses or plateaus, channeled through valleys.

246. Which one among the following forces is most powerful in determining m

Which one among the following forces is most powerful in determining movement of wind including its velocity ?

[amp_mcq option1=”Gravitational force” option2=”Centrifugal force” option3=”Frictional force” option4=”Pressure gradient force” correct=”option4″]

This question was previously asked in
UPSC CAPF – 2011
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The Pressure Gradient Force (PGF) is the primary force that initiates air movement, i.e., wind. It is the force that pushes air from areas of high pressure to areas of low pressure. The strength of the wind is directly proportional to the magnitude of the pressure gradient (the rate of pressure change over distance).
Pressure gradient force is fundamental to atmospheric circulation. Air flows from high pressure to low pressure, and this movement constitutes wind. Other forces like Coriolis force and friction modify the direction and speed of the wind, but PGF is the initial driver.
While other forces influence wind, their roles are different: Gravitational force keeps the atmosphere bound to the Earth. Centrifugal force is relevant in curved motion but not the primary cause of wind. Frictional force acts opposite to the direction of motion, slowing down the wind, especially near the surface.

247. Which one among the following statements relating to a cyclone is not

Which one among the following statements relating to a cyclone is not correct ?

[amp_mcq option1=”It is a wind circulation system with a low pressure at the centre” option2=”It brings about sudden change in weather condition in an area” option3=”Wind movement towards the low pressure centre of a cyclone is clockwise in the northern hemisphere” option4=”It is known as hurricane in West Indies” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2011
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Statement C is incorrect. In the Northern Hemisphere, due to the Coriolis effect, winds in a cyclone (a low-pressure system) spiral *counter-clockwise* towards the centre. In the Southern Hemisphere, they spiral clockwise.
The Coriolis effect, caused by the Earth’s rotation, is responsible for the deflection of moving air (and water). This effect dictates the direction of rotation of large-scale weather systems like cyclones and anti-cyclones in different hemispheres.
A cyclone is indeed a low-pressure wind circulation system (Statement A). Cyclones bring about significant and often sudden changes in weather, including strong winds, heavy rain, and sometimes storm surges (Statement B). Cyclones are known by various names globally depending on the region, such as hurricanes in the Atlantic and Northeast Pacific, typhoons in the Northwest Pacific, and willy-willies off the coast of Northwestern Australia (Statement D).

248. Statement I : The Earth is shaped more like a tangerine. Statement II

Statement I : The Earth is shaped more like a tangerine.
Statement II : The Earth spins faster at the Poles.

[amp_mcq option1=”Both the statements are individually true and statement II is the correct explanation of statement I” option2=”Both the statements are individually true but statement II is not the correct explanation of statement I” option3=”Statement I is true but statement II is false” option4=”Statement I is false but statement II is true” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2011
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Statement I is true, but Statement II is false.
The Earth’s shape is an oblate spheroid, and its rotation speed is greatest at the equator.
Statement I is true; the Earth is not a perfect sphere but is slightly flattened at the poles and bulges at the equator due to centrifugal force from its rotation, a shape often approximated by calling it an oblate spheroid or using the analogy of a tangerine or orange. Statement II is false; the Earth spins at a constant *angular* velocity (completing one rotation in roughly 24 hours), but the *linear* velocity (speed along the surface) is highest at the equator because points on the equator are farthest from the axis of rotation. The linear velocity decreases towards the poles and is essentially zero at the geographical poles which lie on the axis of rotation.

249. Which one of the following can be considered as an initial warning of

Which one of the following can be considered as an initial warning of an approaching Tsunami ?

[amp_mcq option1=”Thundering noise” option2=”Squally winds and rainfall” option3=”Rapid withdrawal of water away from the beach” option4=”Rapid landward movement of water” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2010
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The correct option is C) Rapid withdrawal of water away from the beach.
The most common natural warning sign of an approaching tsunami, particularly for the first wave, is a sudden and significant recession of the sea from the coastline, exposing the seabed. This happens because the trough (low point) of the tsunami wave often reaches the shore before the crest (high point). This is an immediate signal that a large wave is approaching and coastal areas should be evacuated.
A thundering noise can sometimes be heard as the tsunami wave breaks, but the water receding is often the first visible sign. Squally winds and rainfall are associated with meteorological phenomena like cyclones, not tsunamis which are primarily caused by underwater geological events. Rapid landward movement of water *is* the tsunami arriving, not a warning beforehand.

250. Which one of the following pairs is correctly matched ? Tropical C

Which one of the following pairs is correctly matched ?

Tropical Cyclone Location
(a) Hurricane Australia
(b) Willy-Willy Japan
(c) Baguio Philippines
(d) Taifu North Atlantic

[amp_mcq option1=”Hurricane Australia” option2=”Willy-Willy Japan” option3=”Baguio Philippines” option4=”Taifu North Atlantic” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2010
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The correct option is C) Baguio Philippines.
Tropical cyclones are given different regional names:
– **Hurricane:** Used in the North Atlantic Ocean, Northeast Pacific Ocean east of the International Date Line.
– **Willy-Willy:** Used in the region of Northwest Australia.
– **Baguio:** The local name for a tropical cyclone in the Philippines.
– **Taifu (Typhoon):** Used in the Northwest Pacific Ocean west of the International Date Line (affecting East Asia including Japan, Taiwan, Korea, China, Philippines).
Based on these definitions, the pair “Baguio Philippines” is correctly matched.
Although Baguio is the local name in the Philippines, the storms are technically typhoons as per the international nomenclature for that region of the Northwest Pacific. However, “Baguio” is widely associated with cyclones affecting the Philippines. Willy-willy is specific to NW Australia. Taifu (Typhoon) affects a broader region of NW Pacific, not just Japan. Hurricanes are specifically Atlantic/NE Pacific.
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