2013 · GS Paper 1 · Q20(b) · 5 marks

What do you understand by the phenomenon of temperature inversion in meteorology? How does it affect weather and the habitants of the place?

In short

A temperature inversion is a reversal of the normal fall of temperature with height, formed on clear calm nights, in valleys and at fronts, and it stabilises the air, causing fog, smog and frost. It traps pollutants that drive Delhi's winter smog and pushes hill settlements to the warmer middle slopes.

Model answer

Ghissu Editorial · Verified 4 Oct 2026

Introduction
Temperature normally falls with height at about 6.5 degrees C per kilometre. A temperature inversion reverses this, with warm air sitting above cooler surface air like a lid on the atmosphere.
Phenomenon and Conditions of Inversion
Temperature Inversion in a Valley (Nighttime)
Valley inversion at night: cool air drains down the slopes and settles under warmer air
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Radiation inversion

Long, clear, calm winter nights let the ground lose heat fast and chill the air above it, as over the north Indian plains.

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Valley inversion

Cold dense air drains down slopes at night and pools on valley floors beneath warmer air, as in Himalayan and Alpine valleys.

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Frontal and advection inversion

Warm air rides over a cold air mass at a front, or passes over a cold surface or current, as off coastal California.

Effects on Weather and Inhabitants
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Stable weather

The inversion stops air from rising, so convection, clouds and rain are suppressed and the weather stays dry and settled.

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Fog and smog

Trapped moisture and pollutants cause dense winter fog in the Indo-Gangetic plain and Delhi's severe winter smog, as in London's Great Smog of 1952.

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Frost and farming

Valley-floor frost damages crops, so orchards, tea gardens and settlements occupy the warmer middle slopes, the thermal belt.

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Health and transport

Trapped pollutants worsen respiratory illness, while fog delays flights and trains across north India.

Conclusion
Temperature inversion turns a mixing atmosphere into a stable lid, bringing fog, frost and trapped pollution that shape local weather and livelihoods, which makes inversion-aware forecasting and winter air-quality action essential.

This model answer is indicative and the model can make mistakes; please verify key facts independently.

Hand-drawn diagram: How an Inversion Works. How an Inversion Works. Flow: Clear, calm winter night → Ground and lower air chill → Warm layer sits above → Lid stops air rising → Fog, smog trapped below
Diagram: How an Inversion Works

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