Earth Concepts Archives

1. Match List-I with List-II and select the correct answer using the code

Match List-I with List-II and select the correct answer using the code given below the Lists :

List-I
(Natural disaster)

List-II
(Category)

A. Blizzards	1. Terrestrial
B. Soil erosion	2. Atmospheric
C. Tsunami	3. Biological
D. Locusts	4. Aquatic

Code :

A-3, B-4, C-1, D-2

A-3, B-1, C-4, D-2

A-2, B-1, C-4, D-3

A-2, B-4, C-1, D-3

This question was previously asked in

UPSC CISF-AC-EXE – 2024

Download PDF Attempt Online

Matching the natural disasters with their categories:
A. Blizzards are severe snowstorms characterized by strong winds, which are atmospheric phenomena. Thus, Blizzards (A) match with Atmospheric (2).
B. Soil erosion is the denudation of the upper layer of soil, a process occurring on the Earth’s surface, hence a terrestrial phenomenon. Thus, Soil erosion (B) matches with Terrestrial (1).
C. Tsunami is a series of giant waves caused by large-scale disturbances, most commonly underwater earthquakes or volcanic eruptions. As it is a phenomenon related to water bodies, it is categorized as aquatic. Thus, Tsunami (C) matches with Aquatic (4).
D. Locusts are migratory insects that form swarms and can cause massive damage to crops. This involves biological organisms causing a disaster, hence a biological phenomenon. Thus, Locusts (D) match with Biological (3).
The correct matching is A-2, B-1, C-4, D-3, which corresponds to option C.

Natural disasters can be broadly categorized based on their origin, such as atmospheric, terrestrial, aquatic, and biological.

Other examples include: Atmospheric (cyclones, droughts, heat waves), Terrestrial (earthquakes, landslides, volcanic eruptions), Aquatic (floods, storms, sea-level rise), Biological (epidemics, pest infestations). Some disasters can overlap categories or have cascading effects across categories.

2. Consider the following: Electromagnetic radiation Geothermal energy

Consider the following:

Electromagnetic radiation
Geothermal energy
Gravitational force
Plate movements
Rotation of the earth
Revolution of the earth

Which of the above are responsible for bringing dynamic changes on the surface of the earth?

1, 2, 3 and 4 only

1, 3, 5 and 6 only

2, 4, 5 and 6 only

1, 2, 3, 4, 5 and 6

This question was previously asked in

UPSC IAS – 2013

Download PDF Attempt Online

The correct option is D, as all the listed factors are responsible for bringing dynamic changes on the surface of the earth.

– Electromagnetic radiation (primarily from the Sun): Drives climate, weather systems, erosion (through wind, water, ice), photosynthesis (biological weathering), and thermal expansion/contraction (physical weathering).
– Geothermal energy: Drives plate tectonics, volcanic activity, earthquakes, formation of mountains and ocean basins, and heat flow influencing subsurface processes.
– Gravitational force: Causes mass movements (landslides, rockfalls), erosion by rivers (pulling water downhill), formation of tides (along with moon), and influences atmospheric circulation and ocean currents.
– Plate movements: Directly responsible for earthquakes, volcanism, mountain building (orogeny), creation of rift valleys, and continental drift, constantly reshaping the Earth’s crust.
– Rotation of the earth: Causes Coriolis effect (influencing weather patterns, currents), contributes to tides (along with gravity), and diurnal temperature variations causing weathering.
– Revolution of the earth: Along with axial tilt, causes seasons, influencing weather patterns, rates of weathering and erosion, formation and melting of ice/snow, and biological activity.

The Earth’s surface is constantly being altered by both internal (endogenic) and external (exogenic) processes. Geothermal energy and Plate movements are primarily endogenic forces. Electromagnetic radiation, Gravitational force, Rotation, and Revolution of the earth drive exogenic processes like weathering, erosion, and mass wasting, and also influence weather and climate which shape the surface. All these factors interact in complex ways to create the dynamic surface we see.

3. Which one of the following statements about the solstices, an event th

Which one of the following statements about the solstices, an event that occurs when the Sun appears to reach most northerly or southerly, is correct ?

The winter solstice takes place on June 21 in both the northern and southern hemispheres

The winter solstice takes place on December 21 in both the northern and southern hemispheres

The summer solstice occurs in northern hemisphere on June 21 and on December 21 in southern hemisphere

The summer solstice occurs in northern hemisphere on December 21 and on June 21 in southern hemisphere

This question was previously asked in

UPSC CAPF – 2024

Download PDF Attempt Online

Solstices are astronomical events that occur twice a year, marking the points at which the Sun reaches its highest or lowest point in the sky at noon, depending on the hemisphere. This is due to the tilt of the Earth’s axis relative to its orbital plane. The summer solstice occurs around June 20 or 21 in the Northern Hemisphere when the North Pole is tilted towards the Sun, resulting in the longest day of the year. On this same date, it is the winter solstice in the Southern Hemisphere, with the shortest day. Conversely, the winter solstice in the Northern Hemisphere occurs around December 21 or 22 when the North Pole is tilted away from the Sun, marking the shortest day. On this date, it is the summer solstice in the Southern Hemisphere. Therefore, the summer solstice occurs in the Northern Hemisphere on June 21 (approximately) and in the Southern Hemisphere on December 21 (approximately).

Solstices mark the maximum axial tilt of the Earth towards or away from the Sun, leading to the longest and shortest days of the year in the respective hemispheres. The solstices in the Northern and Southern Hemispheres are six months apart.

The dates of the solstices can vary by a day or two each year due to the Earth’s elliptical orbit and the presence of leap years. The other key seasonal markers are the equinoxes (vernal/spring and autumnal), which occur around March 20 and September 22, when the tilt is neither towards nor away from the Sun, resulting in approximately equal day and night length globally.

4. Consider the following statements: 1. Many of the world’s largest mo

Consider the following statements:

1. Many of the world’s largest mountain chains exist beneath the sea.
2. Some mountain chains are revealed as island arcs.
3. The mid-oceanic ridges form the longest mountain chains.
4. The mid-Atlantic ridge rises thirty-three metres above the floor of the Atlantic.

Which of the statements given above are correct?

1 and 2 only

3 and 4 only

1, 2 and 4 only

1, 2 and 3 only

This question was previously asked in

UPSC CAPF – 2023

Download PDF Attempt Online

Statements 1, 2 and 3 are all correct.

Statement 1: Many of the world’s largest mountain chains are indeed located beneath the sea. The most prominent example is the mid-oceanic ridge system. This statement is correct.
Statement 2: Island arcs are curved chains of volcanic islands that are often formed along convergent plate boundaries where one oceanic plate subducts beneath another. These volcanic islands represent the peaks of underwater mountain ranges that have risen above the sea surface. Thus, some mountain chains are revealed as island arcs. This statement is correct.
Statement 3: The mid-oceanic ridge system is a vast underwater mountain range that stretches for over 65,000 kilometers across the globe’s oceans. It is considered the longest mountain chain on Earth. This statement is correct.
Statement 4: The Mid-Atlantic Ridge is a major part of the mid-oceanic ridge system. While it rises significantly above the surrounding abyssal plains, its rise is typically hundreds or thousands of metres, not just thirty-three metres. Most of the Mid-Atlantic Ridge remains submerged, although it surfaces in Iceland. This statement is incorrect.

Mid-oceanic ridges are formed by tectonic plate divergence and volcanic activity. Island arcs are typically associated with deep oceanic trenches and high seismic activity. Submarine mountain chains are significant features of the Earth’s topography and play a crucial role in oceanographic processes.

5. Which one of the following correctly explains the change in seasons on

Which one of the following correctly explains the change in seasons on Earth ?

Tilt of the Earth's axis

Rotation of the Earth on its own axis

Revolution of the Moon around the Sun

Interaction of the Earth with other planets

This question was previously asked in

UPSC CAPF – 2023

Download PDF Attempt Online

The tilt of the Earth’s axis correctly explains the change in seasons on Earth.

The primary cause of the change in seasons on Earth is the tilt of the Earth’s rotational axis relative to its orbital plane (the plane of Earth’s path around the Sun), which is approximately 23.5 degrees. As the Earth revolves around the Sun over the course of a year, the tilted axis means that different parts of the Earth receive more direct sunlight at different times. When a hemisphere is tilted towards the Sun, it receives more direct sunlight and experiences summer, with longer days. When it is tilted away from the Sun, it receives less direct sunlight and experiences winter, with shorter days. The Earth’s revolution around the Sun is necessary for the tilt to cause different hemispheres to be oriented towards or away from the Sun over time.

The Earth’s rotation on its own axis causes the cycle of day and night. The revolution of the Moon around the Earth causes phases of the Moon and tides. The interaction of the Earth with other planets has minor gravitational effects but does not cause the regular seasonal changes. The slight eccentricity of Earth’s orbit means the Earth is closer to the Sun in January (perihelion) and farther in July (aphelion), which has a small influence on temperature but is secondary to the effect of the axial tilt in causing the seasons.

6. Which one among the following statements about ‘Drumlin’ is correct ?

Which one among the following statements about ‘Drumlin’ is correct ?

It is a streamlined hill moulded in glacial drift on the till plains.

It is a city located in central Europe.

It is a river.

It is a narrow road in Tibet.

This question was previously asked in

UPSC CAPF – 2023

Download PDF Attempt Online

The correct answer is A. A drumlin is a glacial landform, specifically a streamlined hill composed of glacial till, molded by ice flow.

– Drumlins are typically elongated features, with their long axis oriented parallel to the direction of glacial movement.
– They are formed beneath glacial ice sheets or glaciers.
– They are composed of unconsolidated glacial drift or till (sediment deposited directly by the glacier).
– Drumlins often occur in fields or swarms, giving a characteristic landscape appearance.

The shape of a drumlin is thought to be a result of the ice molding the underlying sediment as it flows over it. They typically have a blunt, steeper “stoss” end facing up-ice and a tapering, gentler “lee” end pointing down-ice. The term “drumlin” comes from the Irish word “droimnín”, meaning “little ridge”.

7. Which one of the following statements about ‘great circle’ is not corr

Which one of the following statements about ‘great circle’ is not correct?

Every great circle divides the Earth into equal halves.

Every great circle is a circumference of the Earth.

Great circles mark the longest travel routes between locations on the Earth's surface.

Great circle is the largest circle that can be drawn around the Earth through two particular points.

This question was previously asked in

UPSC CAPF – 2022

Download PDF Attempt Online

Great circles represent the shortest travel routes between two points on the surface of a sphere (like Earth). Statement C says they mark the *longest* routes, which is incorrect.

A great circle is the intersection of a sphere and a plane that passes through the center of the sphere. It is the largest possible circle that can be drawn on a sphere.

Every great circle divides the Earth into two equal hemispheres. The equator and all lines of longitude are examples of great circles. Lines of latitude, except for the equator, are not great circles. The shortest distance between two points on the surface of a sphere lies along the arc of the great circle passing through them.

8. If the equatorial plane of earth is NOT inclined to its orbit, then

If the equatorial plane of earth is NOT inclined to its orbit, then

duration of the year would be longer

summer would be warmer

there would be no change of seasons

winter would be longer

This question was previously asked in

UPSC CAPF – 2019

Download PDF Attempt Online

The correct answer is C) there would be no change of seasons.

The primary cause of the Earth’s seasons is the tilt of its rotational axis relative to its orbital plane around the Sun. The Earth’s axis is currently tilted at approximately 23.5 degrees.

* This tilt causes different parts of the Earth to be inclined towards or away from the Sun at different times of the year. When a hemisphere is tilted towards the Sun, it receives more direct sunlight and experiences summer. When it is tilted away, it receives less direct sunlight and experiences winter.
* If the equatorial plane of Earth were *not* inclined to its orbit (meaning the axial tilt was 0 degrees), the amount of sunlight received at any given latitude would be constant throughout the year. The Sun would always appear directly overhead at the equator at noon every day.
* This lack of variation in solar insolation across the year at different latitudes would mean there would be no distinct seasonal changes like summer, winter, spring, and autumn. The temperature and climate at any location would remain relatively stable year-round, primarily varying with latitude.
* Option A is incorrect because the duration of the year is determined by the time it takes for Earth to complete one orbit around the Sun (approximately 365.25 days), which is independent of the axial tilt.
* Options B and D are incorrect because summer and winter, as defined by varying temperatures and daylight hours caused by axial tilt, would not exist in their current form. While temperatures would vary by latitude, they wouldn’t follow the cyclical seasonal pattern caused by tilt.

Without axial tilt, regions near the equator would still be the warmest, and regions near the poles the coldest, due to the angle at which sunlight strikes the surface. However, the annual cycle of warming and cooling associated with the seasons in mid-latitudes would be absent.

9. The antipodal position of a place located at 35° south and 80° west is

The antipodal position of a place located at 35° south and 80° west is :

55° north and 80° east

35° north and 100° east

100° north and 80° east

55° south and 10° east

This question was previously asked in

UPSC CAPF – 2010

Download PDF Attempt Online

The antipodal point of a location (Latitude X, Longitude Y) is found by taking the opposite latitude in the other hemisphere (X in opposite hemisphere) and the longitude that is 180 degrees away in the opposite direction ((180 – Y) in opposite direction). For a point at 35° South and 80° West: The latitude opposite to 35° South is 35° North. The longitude opposite to 80° West is (180° – 80°) = 100° East. Thus, the antipodal position is 35° North and 100° East.

To find the antipodal point: flip the hemisphere of the latitude and subtract the longitude from 180°, flipping the East/West direction.

The antipodal point is the point on the Earth’s surface that is diametrically opposite to a given point. If you were to drill a straight tunnel from one point through the Earth’s center, you would emerge at its antipodal point.

10. Where is the Coriolis Effect the largest ?

Where is the Coriolis Effect the largest ?

At the Equator

At the Tropic of Capricorn and Tropic of Cancer

At the North Pole

At 45 degree latitude in each hemisphere

This question was previously asked in

UPSC NDA-2 – 2024

Download PDF Attempt Online

The correct answer is At the North Pole.

The Coriolis Effect is an apparent force that deflects moving objects (like air currents, ocean currents, projectiles) due to the rotation of the Earth. The magnitude of the Coriolis force is proportional to the sine of the latitude. It is zero at the Equator (latitude 0 degrees) and maximum at the poles (latitude 90 degrees North and South), where sin(90) = 1.

The Coriolis effect causes moving air and water to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This effect is significant in large-scale atmospheric and oceanic circulation patterns, but negligible for small-scale, short-duration phenomena like the movement of a person or a car.