NDA Geography · Teaching notes

Climatology, Atmosphere and Weather — NDA Geography

This is one of the heavyweight chapters in NDA Geography — 57 PYQs across 2017–2026, and the densest-HARD recall strand, because the paper blends two demands: it asks you to TRACE A PROCESS (why does the Coriolis force vanish at the equator? how does a cold front spawn thunderstorms? why is the outer atmosphere hottest yet feels cold?) and to RECALL A NAMED FACT (which local wind is the Mistral? what does Koppen's 'Cfa' mean?). So the chapter teaches in one long arc, from the air column outward and from cause to consequence: (1) Atmospheric layers, composition and aurora — the five shells of the atmosphere, what each is made of, and the solar-wind light show; (2) Insolation, temperature and solar geometry — how the Sun heats the Earth, the lapse rate, and temperature inversion; (3) Atmospheric pressure and winds — pressure belts, the Coriolis force, geostrophic and planetary winds; (4) Humidity, condensation, clouds and precipitation — water in the air, the cloud families, and how rain/snow/sleet/hail form; (5) Cyclones, fronts and local winds — tropical vs temperate cyclones, warm/cold fronts, and the named local winds; (6) Climate classification and zones — Koppen's letter codes and the world's climatic regions. Around 25 concepts, every PYQ tagged. The mechanism concepts (Coriolis, fronts, lapse rate, cyclogenesis) carry most of the HARD marks; the named-fact tables (layers, local winds, Koppen codes, cloud types) are pure recall you must drill to reflex.

Subtopic notes

PYQ weightage by concept

24 concepts · 57 PYQs — where the marks actually sit, so you know what to drill first

Atmospheric Layers, Composition and Aurora12 PYQs · 21%
ConceptPYQsShare
The five layers of the atmosphere47%
The normal lapse rate and the tropopause24%
Composition of the atmosphere24%
Aurora and the origin of the Coriolis effect24%
Regional climate-vegetation and a cold local wind24%
Conditions for a tropical cyclone to formfoundation
Insolation, Temperature and Solar Geometry5 PYQs · 9%
ConceptPYQsShare
How the atmosphere is heated24%
Measuring air temperature and the lapse rate12%
Temperature inversion12%
The angle of the Sun's rays and the solstice12%
Atmospheric Pressure and Winds6 PYQs · 11%
ConceptPYQsShare
Pressure belts and planetary winds24%
The Coriolis force24%
The geostrophic wind12%
Anticyclones12%
Humidity, Condensation, Clouds and Precipitation10 PYQs · 18%
ConceptPYQsShare
Cloud families and rain-bearing clouds35%
Sleet, cloudburst and inversion of rainfall35%
Humidity and relative humidity24%
Condensation forms vs precipitation forms24%
Cyclones, Fronts and Local Winds15 PYQs · 26%
ConceptPYQsShare
Named local winds712%
Tropical vs temperate cyclones611%
Fronts and air masses24%
Climate Classification and Zones8 PYQs · 14%
ConceptPYQsShare
Climate regions and the odd-one-out47%
Koppen's climate classification codes35%
The ITCZ and the tropical climates12%

Formula & revision sheet

0 formulas · 5 reference tables · 25 gotchas across all subtopics — the exam-eve cheat-sheet

Atmospheric Layers, Composition and Aurora

Reference tables (2)

Composition of the atmosphere3 rows
Where / whichDominant gas(es)Note
Lower atmosphereNitrogen ~78%, Oxygen ~21%Argon + CO2 + trace gases make up the rest
Most abundant greenhouse gasCarbon dioxideAbove methane, nitrous oxide, CFCs
NDA 2018 — CO2 is the greenhouse gas in largest concentration.
Exosphere (outermost)Helium and HydrogenThe lightest gases float to the top
NDA 2021 — exosphere = helium + hydrogen.
Regional climate-vegetation and a cold local wind3 rows
FactAnswerNote
Campos / Llanos grasslandsSouth AmericaTropical savanna by local name
Natural vegetation of SE ChinaSubtropical broadleaf evergreen forestWarm, humid south-east
A COLD local windMistralSanta Ana / Chinook / Loo are WARM
NDA 2020 — Mistral is the cold one among warm-wind distractors.

Watch out for (6)

Insolation, Temperature and Solar Geometry

Watch out for (2)

Atmospheric Pressure and Winds

Watch out for (3)

Humidity, Condensation, Clouds and Precipitation

Reference tables (1)

Cloud families and rain-bearing clouds5 rows
CloudFamily / altitudeWeather it brings
CirrusHigh, wispy ice cloudsFair, no rain
CumulusHeaped fair-weather cloudUsually fair; can build up
Nimbus (Nimbostratus)Low, layered rain cloudSteady CONTINUOUS rain
NDA 2018 — Nimbostratus = continuous precipitation; NDA 2021 — nimbus = the rain-bearing cloud.
CumulonimbusTowering storm cloudHeavy showers, thunderstorms
Stratus / StratocumulusLOW clouds (NOT high)Overcast, drizzle
NDA 2024 — Stratus/Nimbostratus/Stratocumulus are LOW clouds, not high.

Watch out for (5)

Cyclones, Fronts and Local Winds

Reference tables (1)

Named local winds8 rows
Local windRegionCharacter
HarmattanWest AfricaNOT Mediterranean (the odd one out)
NDA 2024 — Harmattan is the one NOT related to the Mediterranean.
SiroccoMediterranean (from Sahara)Hot, dusty
MistralMediterranean (Rhone valley)COLD, dry
KhamsinEgypt / MediterraneanHot
ChinookNorth America (Rockies)Warm, dry 'snow-eater'
Santa AnaSouthern CaliforniaHot, dry; causes wildfires
NDA 2026 — Santa Ana wind drives Southern California wildfires.
ShamalMesopotamia / Middle EastWarm, dry
NDA 2019 — Shamal is found in Mesopotamia.
PurgaSiberiaCold blizzard wind
NDA 2018 — Purga blows out from Siberia.

Watch out for (6)

Climate Classification and Zones

Reference tables (1)

Koppen's climate classification codes6 rows
CodeClimate type
AfTropical wet (rainforest)
NDA 2018 — Af = tropical wet.
BWkMid-latitude (cold) desert
CsMediterranean (dry summer)
CfaHumid subtropical
NDA 2019 — Cfa = humid subtropical.
CwgGreat Northern Plains of India (monsoon-influenced warm)
NDA 2023 — Great Northern Plains = Cwg.
DfHumid continental

Watch out for (3)