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Temperature

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1

Learn the Concept

All

Temperature is the degree of hotness of the air — the most basic element of weather and climate, resulting from the way insolation is absorbed and redistributed. Fix the structure: heat is transferred by radiation, conduction, convection and advection; temperature varies horizontally (shown by isotherms, controlled by latitude, altitude, continentality, ocean currents) and vertically (normally falling with height at the lapse rate, but sometimes reversed in a temperature inversion). Understanding temperature distribution underlies pressure, winds, humidity and the whole climatic system.

In One Line
  • Heat transfer: radiation, conduction, convection, advection.
  • Horizontal controls: latitude, altitude, continentality, ocean currents, winds.
  • Isotherms: lines joining places of equal temperature.
  • Vertical: normal lapse rate ~6.5°C/km; inversions reverse it.
Glossary (define-on-first-use)
  • Isotherm: a line joining places of equal temperature.
  • Continentality: the greater temperature range of land interiors vs coasts.
  • Normal (environmental) lapse rate: the actual fall of temperature with height (~6.5°C/km).
  • Temperature inversion: a reversal in which temperature rises with height.
  • Advection: horizontal transfer of heat by moving air.

1. Heating & cooling processes

  • Radiation — the Sun heats the ground (short-wave), and the ground heats the air from below (long-wave); conduction — molecule-to-molecule transfer (air in contact with the ground); convection — vertical transfer by rising warm air; advection — horizontal transfer by winds (e.g. warm/cold air masses). The air is thus heated mainly from below, not directly by the Sun.

2. Horizontal distribution & its controls

  • Latitude (insolation angle) — the primary control (warm equator, cold poles). Altitude — temperature falls with height, so highlands are cool even in the tropics. Continentality — land heats and cools faster than water, so interiors have hot summers, cold winters (large range) while coasts are equable. Ocean currents — warm currents (Gulf Stream) raise coastal temperatures, cold currents (Labrador, Benguela) lower them. Prevailing winds and cloud cover also modify it. Isotherms map the pattern; they bend equatorward over cold areas and poleward over warm areas.
Continentality: coast vs interior (annual range) months (J → D) interior (large range) coast (small range)
Fig 1 — Continental interiors swing between hot summers and cold winters; coasts stay equable.

3. Vertical distribution: lapse rate & inversion

  • Normally temperature falls with height. The normal/environmental lapse rate (ELR) is the actual observed fall, averaging ~6.5°C per km. The adiabatic lapse rate is the cooling of a rising air parcel by expansion (dry ~9.8°C/km, saturated ~5°C/km — detailed in the stability leaf).
  • A temperature inversion is when this is reversed — temperature increases with height. Types: radiation (ground) inversion (clear, calm, dry nights — the ground & air near it cool fast); subsidence inversion (sinking air warms aloft, under high pressure); frontal inversion (warm air rides over cold at a front); and valley inversion (cold dense air drains into valleys at night — causing fog & frost pockets). Inversions trap pollutants and fog.
Valley (air-drainage) temperature inversion cold dense air + fog pools in valley floor warm air above (inversion) slopes cold air drains downslope at night → frost & fog pockets
Fig 2 — At night cold air drains into the valley, placing warm air above cold: a valley temperature inversion.
Inversion typeCause
Radiation (ground)Rapid night cooling of ground (clear, calm)
SubsidenceSinking air warms aloft (high pressure)
FrontalWarm air overrides cold at a front
ValleyCold air drains into valley at night
Key Facts to Remember
  • Heat transfer: radiation, conduction, convection, advection; air heated from below.
  • Horizontal controls: latitude, altitude, continentality, ocean currents, winds; shown by isotherms.
  • Continentality: interiors = large range; coasts = equable.
  • Normal lapse rate ~6.5°C/km; inversion = temperature rises with height.
  • Inversions: radiation, subsidence, frontal, valley — trap fog/pollutants.
Connect the Dots
  • Insolation & heat budget: the source of warmth (neighbouring leaves).
  • Stability & instability: adiabatic lapse rates (later leaf).
  • Pressure & winds: temperature differences drive them.
  • Urban climate: urban heat island & inversions (later leaf).
2

Prepare for the Exam — Prelims

Prelims

Tested on the four heat-transfer modes, the horizontal controls (continentality, currents), isotherm behaviour, the lapse rate, and inversion types.

High-probability areas
  • Heat transfer: radiation, conduction, convection, advection.
  • Air is heated from below (long-wave from ground).
  • Continentality: interior large range; coast equable.
  • Normal lapse rate ~6.5°C/km.
  • Inversions: radiation, subsidence, frontal, valley.
Common traps
  • Advection = horizontal; convection = vertical.
  • Inversion = temp RISES with height.
  • Warm current raises, cold current lowers coastal temp.
  • Isotherms bend equatorward over cold areas.
Revision tip: Transfer (rad/cond/conv/adv) → horizontal (lat/alt/continentality/currents) → vertical (lapse rate / inversion).
2

Prepare for the Exam — Mains

Mains

Optional Paper I / GS Paper I. The examiner rewards the controls on distribution and inversion types.

Likely question types
  • Discuss the factors controlling the horizontal distribution of temperature. (15)
  • Explain temperature inversion and its types. (15)
  • What is continentality and how does it affect temperature? (10)
  • Explain the lapse rate. (10)
Dimensions to cover
  • Heat transfer modes.
  • Horizontal controls & isotherms.
  • Vertical: lapse rate.
  • Inversion types.
Value-additions
  • Gulf Stream vs Labrador.
  • Valley inversion & fog/frost.
  • Inversion & air pollution.
3

How to Write the Answer

Mains
Worked example — decoding the question

“Explain temperature inversion and its geographical significance.” (15)
Define inversion, give the four types, then its effects (fog, frost, pollution).

Introduction · ~20%
Define the normal lapse rate & inversion as its reversal.
Body · ~60%
Types: radiation (ground), subsidence, frontal, valley — each with its cause. Significance: traps fog & pollutants (smog), frost pockets damaging crops, stable clear weather, affects aviation. Use the valley-inversion diagram.
Conclusion · ~20%
Inversions have major effects on fog, pollution and agriculture.
10-mark: ~150 words · ~7 min
15-mark: ~250 words · ~12 min
Common mistakes
  • Confusing advection/convection.
  • Saying inversion lowers temp with height.
  • Ignoring significance.
Model opening line: “Usually the air cools as we climb — but on a still, clear night the order can flip, trapping cold and fog below.”
4

Prelims Questions

Prelims

30 interactive MCQs — previous-year questions are included and tagged with their year. Select an answer for instant feedback and an explanation; your score is tracked and you can review wrong answers at the end.

Practice set
Question 1 of 30
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Score
5

Mains Questions

Mains

15 mains questions — previous-year questions are included and tagged. Write a full answer, then click Evaluate My Answer for paragraph-level feedback. Reveal the model structure after you attempt.

15 marks · ~250 words · ~11 min
Discuss the factors controlling the horizontal distribution of temperature.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

15 marks · ~250 words · ~11 min
Explain temperature inversion, its types and geographical significance.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
What is continentality and how does it affect temperature?
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
Explain the normal lapse rate.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

15 marks · ~250 words · ~11 min
Describe the processes of atmospheric heating and cooling.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
Explain the behaviour of isotherms over land and sea.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
Discuss the effect of ocean currents on temperature.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

15 marks · ~250 words · ~11 min
Analyse the vertical distribution of temperature in the atmosphere.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
Explain valley and radiation inversions.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
How does altitude affect temperature?
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

15 marks · ~250 words · ~11 min
Discuss the role of temperature inversion in fog and air pollution.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
Distinguish between advection and convection.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
Explain why air is heated mainly from below.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

15 marks · ~250 words · ~11 min
Examine the controls on the global pattern of temperature.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

10 marks · ~150 words · ~7 min
Describe the types of temperature inversion.
Evaluate My Answer
Model answer structure

Intro: define the key term and give a one-line context hook.
Body 1: conceptual / historical basis with a named fact, date or example.
Body 2: evidence and analysis — sites, inscriptions, coins, archaeologists.
Body 3: limitations or the counter-view (balanced).
Conclusion: a specific, reasoned judgment / way forward.

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