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Q26 (IAS/2025) Geography › World Physical Geography › Atmosphere composition Answer Verified

Consider the following statements : Statement I : The amount of dust particles in the atmosphere is more in subtropical and temperate areas than in equatorial and polar regions. Statement II : Subtropical and temperate areas have less dry winds. Which one of the following is correct in respect of the above statements?

Result
Your answer: —  ·  Correct: C
Explanation

The correct answer is option C because Statement I is correct but Statement II is incorrect.

Statement I is correct: The higher concentration of dust particles is found in subtropical and temperate regions due to dry winds in comparison to equatorial and polar regions.[1] This is well-established in geographical literature.

However, Statement II is incorrect because it claims that subtropical and temperate areas have **less** dry winds, which is the opposite of reality. The actual reason for higher dust concentration in subtropical and temperate regions is the presence of dry winds[1], not their absence. Subtropical regions around 30° N and 30° S are characterized by high-pressure areas known as subtropical highs[2], which are associated with dry, descending air masses that promote arid conditions and dry winds.

Since Statement II incorrectly attributes less dry winds to these regions when they actually experience more dry winds, it cannot explain Statement I. Therefore, while Statement I is factually correct, Statement II is factually incorrect, making option C the correct choice.

Sources
  1. [1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 7: Composition and Structure of Atmosphere > Dust Particles > p. 65
  2. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 9: Atmospheric Circulation and Weather Systems > World Distribution of Sea Level Pressure > p. 77
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Q. Consider the following statements : Statement I : The amount of dust particles in the atmosphere is more in subtropical and temperate a…
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Origin: Books + Current Affairs Fairness: Low / Borderline fairness Books / CA: 3.3/10 · 3.3/10
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This is a 'Line-by-Line' lift from NCERT Class XI Fundamentals of Physical Geography, Chapter 7. It proves that UPSC still rewards deep reading of basic texts over complex current affairs materials. If you skipped the 'Dust Particles' paragraph thinking it was trivial, you lost 2 marks.

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
Are atmospheric dust particle concentrations higher in subtropical and temperate regions than in equatorial and polar regions?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 7: Composition and Structure of Atmosphere > Dust Particles > p. 65
Presence: 5/5
“Atmosphere has a sufficient capacity to keep small solid particles, which may originate from different sources and include sea salts, fine soil, smoke-soot, ash, pollen, dust and disintegrated particles of meteors. Dust particles are generally concentrated in the lower layers of the atmosphere; yet, convectional air currents may transport them to great heights. The higher concentration of dust particles is found in subtropical and temperate regions due to dry winds in comparison to equatorial and polar regions. Dust and salt particles act as hygroscopic nuclei around which water vapour condenses to produce clouds.”
Why this source?
  • Directly states that higher concentration of dust particles is found in subtropical and temperate regions
  • Specifically contrasts these regions with equatorial and polar regions
  • Attributes the pattern to dry winds, providing a causal link
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 23: Pressure Systems and Wind System > Formation > p. 312
Presence: 4/5
“• As this region lies along the equator, it receives highest amount of insolation. Due to intense heating, the air gets heated up creating a low-pressure region (thermally formed). • After the complete loss of moisture, the air moving away from the equatorial low-pressure belt and the subtropical low-pressure belt in the upper troposphere is dry and cold. The blocking effect of air at upper levels because of the Coriolis force forces the cold, dry air to subside at 30° N and S. So, the high pressure (dynamically formed) along this belt is due to subsidence of air coming from the equatorial region and the subpolar region.”
Why this source?
  • Explains subsidence of dry air around 30° N and S that produces high-pressure, dry conditions
  • Provides a dynamical mechanism (air subsiding from equator) that favors dry winds able to carry dust
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 9: Atmospheric Circulation and Weather Systems > World Distribution of Sea Level Pressure > p. 77
Presence: 3/5
“The world distribution of sea level pressure in January and July has been shown in Figures 9.2 and 9.3. Near the equator the sea level pressure is low and the area is known as equatorial low. Along 30° N and 30o S are found the high-pressure areas known as the subtropical highs. Further pole wards along 60o N and 60o S, the low-pressure belts are termed as the sub polar lows. Near the poles the pressure is high and it is known as the polar high. These pressure belts are not permanent”
Why this source?
  • Identifies the latitudinal pressure belts: equatorial low, subtropical highs, and polar highs
  • Supports the latitudinal contrast in atmospheric conditions (dry subtropics vs. moist equator/polar zones)
Statement analysis

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Statement analysis

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SIMILAR QUESTIONS

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Assertion (A): The amount of dust particles is less in subtropical and temperate areas than in equatorial area. Reason (R): The atmosphere is dry and windy in the subtropical and temperate areas.

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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 ?

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Consider the following statements : Statement-I : The atmosphere is heated more by incoming solar radiation than by terrestrial radiation. Statement-II : Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long wave radiation. Which one of the following is correct in respect of the above statements ?

NDA-II · 2013 · Q63 Relevance score: 0.86

Which of the following statements is/are correct? 1. Air close to the Earth’s surface heavier. 2. Air close to the Earth’s surface contains larger quantity of water vapoor and dust particles Select the correct answer using the code given below :