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General Studies 2022 GS Paper I 15 marks 250 words Compulsory Explain

GS Paper I — Q17

Troposphere is a very significant atmospheric layer that determines weather processes. How ? (Answer in 250 words) 15

हिंदी में प्रश्न पढ़ें

क्षोभमंडल वायुमंडल का एक महत्वपूर्ण परत है जो मौसम प्रक्रियाओं को निर्धारित करता है। कैसे ? (250 शब्दों में उत्तर दें)

Q17 of the 2022 UPSC Mains General Studies GS Paper I, as printed
The question as printed in the 2022 General Studies paper
Evaluate your answer to this question → See all 2022 General Studies questions

Model answer

Written by UPSC Answer Check against this question's marking rubric, to the 250-word length. UPSC does not publish answers for Mains — this is one way to score well, not an official key.

The troposphere, the lowest atmospheric layer extending from Earth’s surface to about 8–18 km, determines weather because it contains nearly all atmospheric water vapour—about 99%—and hosts the temperature, pressure and motion contrasts that drive atmospheric change. Its average environmental lapse rate of about 6.5°C per km makes warmer, moist air near the surface less dense than air above, producing instability and convection. This lifts air, cools it adiabatically, condenses vapour into clouds and releases latent heat, intensifying thunderstorms, monsoon bursts and tropical cyclones.

Pressure gradients set air in motion, while the Coriolis force deflects it, generating planetary, regional and local winds. In India, the seasonal shift of the Inter-tropical Convergence Zone and pressure contrasts between land and ocean drive the southwest monsoon; winter westerlies bring Western Disturbances to the northwest; and warm oceanic energy fuels cyclones over the Bay of Bengal and Arabian Sea. The tropopause, the upper boundary of the troposphere, generally limits the vertical development of most weather systems, although intense cumulonimbus towers may overshoot into the lower stratosphere.

These processes make the troposphere central to aviation safety, as turbulence, jet streams and convective activity affect flight planning; to agriculture, through rainfall, heat and frost; and to disaster management, through forecasting of floods, cyclones and heatwaves. IMD’s radiosonde, satellite and radar monitoring of these layers underpins nowcasting and seasonal outlooks. Thus, by concentrating moisture, energy and motion, the troposphere is the active engine of weather, and its changing structure under climate change makes monitoring essential for forecasting and mitigation.

What "Explain" is asking you to do

Make the working of something clear — what sets it off, what follows from what, and what it produces. Explain is the Commission's mechanism word: it dominates the technical papers and the “explain why” stems, where the marks sit in the causal chain and not in the label.

Structure that answers it

State what it is → the initiating condition → the chain of cause, step by step → an instance where it plays out → what the chain produces

Where marks are lost

Describing what something looks like instead of why it works that way. Naming the stages without linking them reads as description too.

All UPSC directive words, compared →

How this answer will be evaluated

Approach

Framework: Geography: explain the mechanism, then location follows. explain: definition/context > points in order > small example > short close Full marks: Detailed mechanism of convection, water vapor, and surface interaction.

Key points expected

  • Vertical temperature gradient (lapse rate) driving convection
  • Presence of water vapor and clouds
  • Interaction with Earth's surface (friction/heat)
  • Role of atmospheric pressure and wind systems

Evaluation rubric

Each sub-part is marked on its own, against the marks and word limit printed on the paper.

  1. The answer Explain the physical and chemical mechanisms by which the troposphere drives weather. 15 marks · 250 words

    explain— definition/context → points in order → small example → short close

    Must cover

    • Vertical temperature gradient (lapse rate) driving convection
    • Presence of water vapor and clouds
    • Interaction with Earth's surface (friction/heat)
    • Role of atmospheric pressure and wind systems

    Loses marks

    • Describing only the layers without mechanism
    • Confusing troposphere with stratosphere
    • Ignoring the role of water vapor

    Earns more

    • Mention of tropopause as a boundary
    • Link to greenhouse effect
    • Reference to jet streams
    • Distinction from stratosphere

    Extra mark

    • Sketch of atmospheric layers
    • Specific lapse rate value (6.5°C/km)

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