Earth Concepts

11. The Coriolis effect is the result of

The Coriolis effect is the result of

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Pressure gradient
Earth's axis of inclination
Earth's rotation
Earth's revolution
This question was previously asked in
UPSC NDA-2 – 2017
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The Coriolis effect is the result of the Earth’s rotation.
The Coriolis effect is an apparent force (a fictitious force in a rotating reference frame) that deflects moving objects like winds, ocean currents, and missiles from their intended straight path. It is a consequence of observing motion from a rotating frame of reference, specifically the Earth. In the Northern Hemisphere, it causes deflection to the right; in the Southern Hemisphere, it causes deflection to the left.
While pressure gradients drive atmospheric and oceanic movements, it is the Earth’s rotation that causes the Coriolis deflection of these movements. The Earth’s axis of inclination is responsible for seasons, and the Earth’s revolution around the sun also contributes to seasons.

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12. Which of the following is/are environmental effects of Rotation of the

Which of the following is/are environmental effects of Rotation of the Earth ?

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  • 1. Daily or diurnal rhythm in day-light and air temperature
  • 2. Flow path of both air and water are turned consistently in a side-ward direction
  • 3. The movement of the tides

Select the correct answer using the code given below :

1 and 2 only
1 and 3 only
1, 2 and 3
3 only
This question was previously asked in
UPSC NDA-1 – 2019
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The rotation of the Earth on its axis has several significant environmental effects. These include:
1. Creating the cycle of day and night, leading to diurnal variations in sunlight and thus air temperature (daily rhythm).
2. Causing the Coriolis effect, which deflects moving objects (like air and water currents) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This influences wind patterns, ocean currents, and even the flow of rivers over long distances.
The movement of tides is primarily caused by the gravitational pull of the Moon and the Sun. While Earth’s rotation influences the timing and frequency of tides experienced at a particular location, the tidal bulges themselves are a result of gravitational forces, not Earth’s rotation directly causing the water movement as its primary effect in this context.
– Rotation causes day-night cycles (diurnal rhythm).
– Rotation causes the Coriolis effect, deflecting air and water flows.
– Tides are primarily caused by gravitational forces from the Moon and Sun.
The Coriolis effect is a fundamental concept in meteorology and oceanography, explaining large-scale weather patterns like cyclones and the direction of ocean currents. The interaction of Earth’s rotation with tidal forces contributes to phenomena like tidal currents and the timing of high/low tides, but the fundamental cause of the tidal bulge is gravity.

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13. Which of the following statements in the context of northern hemispher

Which of the following statements in the context of northern hemisphere is/are correct ?

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  • 1. Vernal equinox occurs on March 21.
  • 2. Summer solstice occurs on December 22.
  • 3. Autumnal equinox occurs on September 23.
  • 4. Winter solstice occurs on June 21.

Select the correct answer using the code given below :

1 only
1 and 3 only
2 and 4 only
1, 2 and 3 only
This question was previously asked in
UPSC NDA-1 – 2016
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The correct option is B.
Let’s evaluate each statement in the context of the Northern Hemisphere:
1. Vernal equinox occurs around March 20 or 21. This is when the sun is directly over the equator, resulting in approximately equal day and night length everywhere on Earth. In the Northern Hemisphere, this marks the start of spring. This statement is correct.
2. Summer solstice occurs around June 20 or 21. This is when the sun is directly over the Tropic of Cancer (23.5° N), resulting in the longest day and shortest night in the Northern Hemisphere. Statement 2 says it occurs on December 22, which is the date for the *Winter* Solstice in the Northern Hemisphere. This statement is incorrect.
3. Autumnal equinox occurs around September 22 or 23. Like the vernal equinox, the sun is directly over the equator, resulting in approximately equal day and night length. In the Northern Hemisphere, this marks the start of autumn. This statement is correct.
4. Winter solstice occurs around December 21 or 22. This is when the sun is directly over the Tropic of Capricorn (23.5° S), resulting in the shortest day and longest night in the Northern Hemisphere. Statement 4 says it occurs on June 21, which is the date for the *Summer* Solstice in the Northern Hemisphere. This statement is incorrect.
Therefore, only statements 1 and 3 are correct.
The dates of equinoxes and solstices can vary slightly each year due to the Earth’s elliptical orbit and the occurrence of leap years. The terms “vernal” and “autumnal” refer to the seasons in the Northern Hemisphere; in the Southern Hemisphere, the seasons are reversed, so the March equinox is the autumnal equinox and the September equinox is the vernal equinox.

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14. To a perpendicular to the plane of ecliptic, Earth’s axis of rotation

To a perpendicular to the plane of ecliptic, Earth’s axis of rotation makes an angle of 23½ degrees. Had this angle been zero degree, which one among the following would result ?
A) There would have been no season
B) The length of day and night would have been the same throughout the year
C) The length of the day and night would have been the same all over the earth
D) All of the above

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There would have been no season
The length of day and night would have been the same throughout the year
The length of the day and night would have been the same all over the earth
All of the above
This question was previously asked in
UPSC NDA-1 – 2015
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If Earth’s axis of rotation made an angle of zero degrees with the perpendicular to the plane of the ecliptic, it would mean the axis is perpendicular to the orbital plane. This configuration would eliminate the tilt that causes seasons. With no tilt, the sun’s rays would be directly overhead at the equator throughout the year. Consequently, every point on Earth would experience approximately 12 hours of daylight and 12 hours of darkness every day of the year, and there would be no significant seasonal variations in temperature or day length at any given latitude.
The tilt of Earth’s axis of rotation (currently 23.5 degrees) is the primary cause of seasons, varying day lengths throughout the year at latitudes away from the equator, and varying angles of incidence of solar radiation.
A zero-degree tilt would mean the terminator (the line separating day from night) would always pass through the poles. This would result in uniform day/night lengths of 12 hours everywhere on Earth throughout the year and the absence of distinct seasons.

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15. Eratosthenes, a Greek philosopher measured the Earth’s circumference b

Eratosthenes, a Greek philosopher measured the Earth’s circumference based on the angle of Sun rays at two different points. Which cities were they ?

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Alexandria and Syene
Syene and Troy
Alexandria and Troy
Alexandria and Thebes
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UPSC CDS-2 – 2024
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The Greek mathematician, geographer, and astronomer Eratosthenes is famous for calculating the circumference of the Earth around 240 BC. He did this by observing the angle of the sun’s rays at noon on the summer solstice in two different Egyptian cities, Syene (modern Aswan), where the sun was directly overhead (no shadow in a well), and Alexandria, where the sun’s rays cast a shadow at a measurable angle. He then used the distance between the two cities and basic geometry to estimate the Earth’s circumference.
Eratosthenes was one of the first to accurately estimate the size of the Earth using geometrical principles and astronomical observations.
Syene is located close to the Tropic of Cancer. On the summer solstice, the sun is directly overhead at noon along the Tropic of Cancer. Alexandria is located north of the Tropic of Cancer, so the sun would not be directly overhead there. The difference in the angle of the sun’s rays at the two locations allowed Eratosthenes to calculate the curvature of the Earth and subsequently its circumference.

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16. Which of the following statements is/are correct? 1. Angular velocit

Which of the following statements is/are correct?

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  • 1. Angular velocity for all locations on the Earth’s surface is the same while linear velocity varies.
  • 2. Linear velocity is maximum at the equator and minimum at the poles.

Select the correct answer using the code given below.

1 only
2 only
Both 1 and 2
Neither 1 nor 2
This question was previously asked in
UPSC CDS-1 – 2024
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Both 1 and 2 are correct.
Angular velocity (ω) is uniform for all points on a rotating rigid body (like the Earth) as they complete one rotation in the same time. Linear velocity (v) is related to angular velocity by v = rω, where r is the perpendicular distance from the axis of rotation.
At the equator, ‘r’ is the maximum (Earth’s radius), resulting in maximum linear velocity. At the poles, ‘r’ is zero, resulting in zero linear velocity. Therefore, angular velocity is constant across the Earth’s surface, while linear velocity varies with latitude, being maximum at the equator and minimum (zero) at the poles.

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17. Which one of the following land surfaces has the highest albedo?

Which one of the following land surfaces has the highest albedo?

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A snow covered mountain
A barren rocky piedmont surface
A sandy desert
A mangrove forest
This question was previously asked in
UPSC CDS-1 – 2022
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Albedo is a measure of the reflectivity of a surface. Surfaces with high albedo reflect a large proportion of incoming solar radiation, while surfaces with low albedo absorb more. Among the given options, a snow-covered mountain, especially with fresh snow, has the highest albedo (typically 80-90%). A sandy desert (20-40%), a barren rocky surface (variable, but generally lower than snow), and a mangrove forest (10-20%) have significantly lower albedos.
Fresh snow is one of the most reflective natural surfaces on Earth.
Albedo plays a significant role in climate and temperature regulation. High albedo surfaces reflect sunlight, helping to keep temperatures cooler, while low albedo surfaces absorb sunlight, warming the surface and the surrounding air. The ice-albedo feedback loop is a critical component of climate change understanding.

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18. Which one of the following statements with regard to the winter solsti

Which one of the following statements with regard to the winter solstice is correct?

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The South Pole experiences 24 hours of darkness.
It occurs on June 21.
The North Pole experiences 24 hours of darkness.
The Sun is at aphelion.
This question was previously asked in
UPSC CDS-1 – 2017
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The winter solstice in a hemisphere occurs when that hemisphere is tilted farthest away from the Sun. For the Northern Hemisphere, this happens around December 21st or 22nd. For the Southern Hemisphere, this happens around June 20th or 21st. Unless specified, questions about “winter solstice” often implicitly refer to the Northern Hemisphere winter solstice.
– Statement A: The South Pole experiences 24 hours of darkness. During the Northern Hemisphere winter solstice (around Dec 21/22), the South Pole is tilted towards the Sun and experiences 24 hours of daylight. This statement is incorrect.
– Statement B: It occurs on June 21. June 21 is the summer solstice in the Northern Hemisphere and the winter solstice in the Southern Hemisphere. Assuming the question refers to the Northern Hemisphere winter solstice, this statement is incorrect.
– Statement C: The North Pole experiences 24 hours of darkness. During the Northern Hemisphere winter solstice (around Dec 21/22), the North Pole is tilted away from the Sun, resulting in the Sun not rising above the horizon for 24 hours (polar night). This statement is correct.
– Statement D: The Sun is at aphelion. Aphelion is the point in Earth’s orbit when it is farthest from the Sun, which occurs around July 4th. Solstices are determined by Earth’s axial tilt relative to its orbit, not its distance from the Sun. This statement is incorrect.
The tilt of Earth’s axis (approximately 23.5 degrees) causes the seasons. Solstices mark the points in Earth’s orbit where the tilt is maximum towards or away from the Sun, leading to the longest and shortest days of the year outside the tropics.

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