Authentic Classroom Explanation by IAS Monk

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📌 Question

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?
(a) Both Statement I and Statement II are correct and Statement II explains Statement I
(b) Both Statement I and Statement II are correct but Statement II does not explain Statement I
(c) Statement I is correct but Statement II is not correct
(d) Statement I is not correct but Statement II is correct

✅ Correct Answer: (c) Statement I is correct but Statement II is not correct

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🎯 Theme of the Question

Physical Geography | Atmosphere | Dust Particles | Planetary Wind Belts

This is a conceptual climatology question, testing understanding of winds, aridity, and dust distribution rather than mere facts.

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🧠 Classroom Explanation

Dust particles in the atmosphere are influenced by:

• Dryness of surface
• Strength of winds
• Vegetation cover
• Rainfall frequency

Let us evaluate both statements carefully.

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🟢 Statement I

The amount of dust particles is more in subtropical and temperate areas than in equatorial and polar regions.

✔️ Correct

Why?

• Subtropical regions (20°–35° latitudes) host:
  • Deserts (Sahara, Arabian, Australian)
  • Semi-arid lands
• These regions experience:
  • Sparse vegetation
  • Loose, dry soil
  • Frequent wind action

➡️ Result: High dust availability and suspension

In contrast:

• Equatorial regions:
  • Heavy rainfall washes dust out (wet deposition)
  • Dense vegetation binds soil
• Polar regions:
  • Snow and ice cover
  • Very limited loose material

Hence, dust concentration is lower there.

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🔴 Statement II

Subtropical and temperate areas have less dry winds.

❌ Incorrect

In fact, the opposite is true.

• Subtropical regions are dominated by:
  • Trade winds
  • Westerlies
  • Descending air of subtropical high-pressure belts
• These winds are:
  • Dry
  • Strong
  • Efficient dust carriers

📌 Examples:

• Harmattan winds (West Africa)
• Dust storms in Central Asia
• Westerlies carrying dust across continents

So Statement II is factually wrong.

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🧮 UPSC Assertion–Reason Logic

• Statement I → ✔️ Correct
• Statement II → ❌ Incorrect

👉 Option (c) is the only logically consistent answer.

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🧠 Memory Hook

“Dust loves DRY + WINDY zones”

• Dry land → loose particles
• Wind → suspension & transport
• Rain + vegetation → dust killers

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🔍 Curiosity Corner

Did you know?

• Saharan dust travels:
  • Across the Atlantic
  • Reaches the Amazon Basin
  • Supplies nutrients like phosphorus to rainforests 🌱

UPSC may indirectly test this via:

Dust → Climate → Biogeochemical cycles

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📘 Enrichment Note

Factors controlling atmospheric dust:

1. Aridity
2. Wind velocity
3. Vegetation cover
4. Rainfall intensity
5. Human activity (ploughing, mining)

This question tests Factor 1 + 2 together.

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🎯 Prelims Strategy Insight

• In assertion–reason type questions:
  • Never assume symmetry
  • Read Statement II independently
• UPSC often traps by reversing causation words like:
  • more / less
  • dry / moist

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🧩 One-Line Ready Recall

More dust = Dry land + Strong winds, not rainfall-rich zones.

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🧭 IAS Monk Whisper
What rain washes away, wind proudly carries across continents.