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Q2 (IAS/2024) Geography › World Physical Geography › Atmospheric structure Official Key

Consider the following statements : Statement-I : Thickness of the troposphere at the equator is much greater as compared to poles. Statement-II : At the equator, heat is transported to great heights by strong convectional currents. Which one of the following is correct in respect of the above statements ?

Result
Your answer: —  ·  Correct: A
Explanation

The correct answer is option A because both statements are accurate and Statement-II correctly explains Statement-I.

The troposphere extends to about 8 km at the poles and approximately 18 km at the[1] equator[2], confirming that Statement-I is correct—the troposphere is indeed much thicker at the equator.

The thickness of the troposphere is greatest at the equator because heat is transported to great heights by strong convectional currents[2], which validates Statement-II and establishes the causal relationship. The greater thickness at the equator occurs because heated air rises to greater heights[1], demonstrating that the strong convectional currents mentioned in Statement-II directly cause the increased thickness described in Statement-I.

Therefore, both statements are factually correct, and Statement-II provides the scientific explanation for the phenomenon described in Statement-I, making option A the appropriate choice.

Sources
  1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Troposphere (0 to 12 km) > p. 274
  2. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 7: Composition and Structure of Atmosphere > STRUCTURE OF THE ATMOSPHERE > p. 65
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Don’t just practise – reverse-engineer the question. This panel shows where this PYQ came from (books / web), how the examiner broke it into hidden statements, and which nearby micro-concepts you were supposed to learn from it. Treat it like an autopsy of the question: what might have triggered it, which exact lines in the book matter, and what linked ideas you should carry forward to future questions.
Q. Consider the following statements : Statement-I : Thickness of the troposphere at the equator is much greater as compared to poles. St…
At a glance
Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10
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This is the definition of a 'Sitter'. It is a verbatim copy-paste from NCERT Class XI Fundamentals of Physical Geography. If you missed this, you are neglecting the absolute basics in favor of complex materials. Stop chasing current affairs until your NCERT geography is bulletproof.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
Is the thickness of the Earth's troposphere at the equator significantly greater than the troposphere thickness at the poles?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Troposphere (0 to 12 km) > p. 274
Presence: 5/5
“• The altitude of the troposphere is 8 km at the poles and 18 km at the equator. The troposphere ends with tropopause (the topmost layer of the troposphere marked by constant temperatures). The thickness is greater at the equator because of the heated air that rises to greater heights.”
Why this source?
  • Gives numeric altitudes: 8 km at the poles and 18 km at the equator.
  • Explicitly attributes greater thickness at the equator to heated air rising to greater heights.
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 7: Composition and Structure of Atmosphere > STRUCTURE OF THE ATMOSPHERE > p. 65
Presence: 5/5
“The atmosphere consists of different layers with varying density and temperature. Density is highest near the surface of the earth and decreases with increasing altitude. The column of atmosphere is divided into five different layers depending upon the temperature condition. They are: troposphere, stratosphere, mesosphere, thermosphere and exosphere. The troposphere is the lowermost layer of the atmosphere. Its average height is 13 km and extends roughly to a height of 8 km near the poles and about 18 km at the equator. Thickness of the troposphere is greatest at the equator because heat is transported to great heights by strong convectional currents.”
Why this source?
  • States average troposphere height (13 km) and specific extents: ~8 km near poles and ~18 km at equator.
  • Explains greatest thickness at equator results from heat-driven convection transporting air to greater heights.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Structure of the Atmosphere > p. 7
Presence: 5/5
“Near the equator, because of intense heating from below, the tropopause (upper limit of troposphere) occurs at 18 km; in the middle latitudes, it occurs at 13 km and at the North and South Poles it is only 8 km or less above Earth's surface. In the troposphere, temperatures decrease with increasing altitude at an average rate of 6.4°C per km which is known as the normal lapse rate. In terms of temperature the upper limit of troposphere is –57°C (Fig.1.2).• 2. Stratosphere and Ozonosphere: A layer of the Earth's atmosphere, above the troposphere, extends from about 20 to 50 kms above the sea level.”
Why this source?
  • Specifies tropopause altitude: 18 km at equator, 13 km in mid-latitudes, ~8 km at poles.
  • Links intense equatorial heating to a higher tropopause (thus thicker troposphere).
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