🌍 Physical Geography — Complete Study Notes

B.A. (Hons) Geography | Semester I | Paper Code: 2292101101 | NEP-DSC

Compiled from official syllabus + Previous Year Question Papers (5072, 540)

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📋 Paper Snapshot

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📊 Syllabus → Weightage Map

UNIT I (Intro & Earth System) ████░░░░░░░░░░░░░░░░ 4 Hrs UNIT II (Atmosphere) ████████████████░░░░ 16 Hrs UNIT III (Lithosphere) ████████████████░░░░ 16 Hrs UNIT IV (Hydrosphere) ████████████░░░░░░░░ 12 Hrs UNIT V (Biosphere) ████████████░░░░░░░░ 12 Hrs

Exam pattern insight: Every paper reliably draws one question from each unit — meaning if you prepare all 5 units solidly, you comfortably have 5 attemptable questions no matter which paper you get.

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🔥 Most Repeated Questions (Frequency Chart)

Internal structure of Earth (seismic evidence) ██████████ 2× Insolation / factors affecting it ██████████ 2× Isostasy (define + adjustment/Airy) ██████████ 2× Composition & structure of atmosphere ██████████ 2× Components of Earth System ██████████ 2× Tides / types of tides ██████████ 2× Scope / Nature of Physical Geography ██████████ 2× Folding – types █████ 1× Vegetation distribution & variation █████ 1× Pressure belts & global wind system █████ 1× Ocean currents & factors █████ 1× Soil formation factors █████ 1× Biomes – characteristics █████ 1×

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🗂️ Table of Contents

1. Unit I — Physical Geography & Earth System
2. Unit II — Atmosphere
3. Unit III — Lithosphere
4. Unit IV — Hydrosphere
5. Unit V — Biosphere
6. Full Previous-Year Question Bank
7. Rapid Revision Sheet

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🟦 UNIT I — Physical Geography: Definition, Nature, Scope, Earth as a System (4 Hrs)

1. Definition of Physical Geography

Physical Geography is the branch of geography that studies the natural features and processes of the Earth's surface — landforms, climate, water bodies, soils, and vegetation — and the physical laws underlying them.

Key definitions to quote:

• Strabo: Geography describes the physical features of the earth and its inhabitants.
• Arthur Holmes: Physical geography deals with the description and explanation of Earth's physical features.
• Hartshorne: Geography is concerned with the areal differentiation of the earth's surface.

2. Nature of Physical Geography

• Empirical, systematic, and analytical science.
• Interdisciplinary — draws from geology, meteorology, oceanography, pedology, and biology.
• Follows the scientific method: observation → classification → explanation → prediction.
• Studies spatial (where) and temporal (how it changes over time) patterns of natural phenomena.
• Bridges natural sciences and human geography (forms the base for environmental studies).

3. Scope of Physical Geography

4. Earth as a System

The Earth functions as an integrated system of interacting spheres, exchanging matter and energy continuously (a "systems approach").

5. Components of the Earth System

Interlinkages (why "system"):

• Atmosphere ↔ Hydrosphere: evaporation, precipitation (hydrological cycle).
• Lithosphere ↔ Biosphere: soil supports vegetation; roots weather rock.
• Atmosphere ↔ Lithosphere: weathering, erosion by wind.
• All spheres exchange energy driven by solar insolation, making Earth a dynamic equilibrium (open) system.

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🟩 UNIT II — Atmosphere (16 Hrs)

A. Composition and Structure of the Atmosphere

Composition (by volume, dry air):

Structure (vertical layers):

B. Insolation (Incoming Solar Radiation)

Factors Affecting Insolation / Temperature Distribution:

Heat Budget of the Earth: Earth maintains energy balance — incoming solar radiation = outgoing terrestrial radiation (on an annual average), keeping global temperature stable.

100 units Incoming Solar Radiation ├─ 35 units reflected back (Albedo: clouds 27, atmosphere 6, surface 2) ├─ 14 units absorbed by atmosphere └─ 51 units absorbed by Earth's surface → Surface re-radiates as long-wave (terrestrial) radiation → Balanced by radiation + conduction + convection + latent heat loss

C. Pressure Belts and Global Wind System

Pressure Belts (idealized):

Global Wind System (surface winds):

• Winds are deflected by the Coriolis Effect (right in N. Hemisphere, left in S. Hemisphere — Ferrel's Law).
• Three-cell circulation model: Hadley Cell (0–30°), Ferrel Cell (30–60°), Polar Cell (60–90°).

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🟧 UNIT III — Lithosphere (16 Hrs)

A. Internal Structure of the Earth (Seismic Evidence)

Seismic waves (P and S waves) change velocity/direction at boundaries of different density material, revealing internal layering.

Key seismic proofs:

• Shadow Zone: Region 103°–142° from earthquake focus receives no direct P-waves and no S-waves — proves the core is liquid and refracts waves.
• Gutenberg Discontinuity: boundary between mantle and outer core (~2900 km).
• Lehmann Discontinuity: boundary between outer and inner core (~5150 km).

B. Isostasy

Analogy: Icebergs floating in water — thicker/lighter crust rises higher, denser/thinner crust sits lower.

Two Classical Theories:

Isostatic Adjustment: When load is added (ice sheets, sediment) or removed (erosion, melting glaciers), the crust sinks or rises to restore equilibrium — e.g., post-glacial rebound in Scandinavia after ice-age glaciers melted.

C. Earth's Movements — Endogenic Forces (Folding & Faulting)

Folding: Bending of rock strata due to compressional (horizontal) forces, producing wave-like undulations.

Types of Folds:

Faulting: Fracturing of rocks with displacement of blocks along the fracture (fault plane), due to tensional, compressional, or shearing stress.

(Exogenic forces — weathering, erosion by water/wind/ice — act to wear down these structures; part of the same unit's syllabus scope.)

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🟦 UNIT IV — Hydrosphere (12 Hrs)

A. Hydrological Cycle

The continuous circulation of water between atmosphere, land, and ocean.

Key processes: Evaporation → Condensation → Precipitation → Infiltration → Runoff → back to Ocean. Driven by solar energy and gravity; keeps freshwater renewable.

B. Ocean Currents

Factors Affecting Ocean Currents:

Types: Warm currents (flow from equator to poles, e.g., Gulf Stream) and Cold currents (flow from poles to equator, e.g., Labrador, Peru/Humboldt).

C. Tides

Types of Tides:

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🟪 UNIT V — Biosphere (12 Hrs)

A. Factors Affecting Soil Formation

Soil forms through weathering of parent rock combined with organic input over time — classically summarized by Jenny's equation: S = f(cl, o, r, p, t)

B. Biomes of the Earth — Characteristics

C. Vegetation Distribution & Its Variation ("large variations" argument)

Global vegetation distribution varies enormously because it responds to multiple interacting controls, not a single factor:

Validation points:

• Latitudinal variation: dense equatorial rainforest → savanna → desert → temperate forest → taiga → tundra, moving from equator to poles.
• Altitudinal variation: vegetation belts change with elevation on a single mountain (tropical at base → alpine/tundra-like at summit) — mirrors latitudinal zonation ("altitude mimics latitude").
• Rainfall gradient: rainforest (>2000mm) vs. grassland (250-750mm) vs. desert (<250mm).
• Soil & drainage: mangroves in saline coastal soils vs. conifers in acidic, well-drained mountain soils.
• Human impact: deforestation, agriculture, and urbanization alter natural vegetation cover, adding further variation.

This multi-causal, multi-scalar control validates that vegetation distribution shows very large global variation.

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📚 Full Previous-Year Question Bank (Unit-wise, All 3 Papers Combined)

Unit I Questions

• Define Physical Geography. Discuss the nature and scope of Physical Geography. (Paper 5072/2292101101, Q1)
• Explain different components of earth system. (Paper 5072/2292101101, Q2)
• What are the different components of Earth System? Describe them in detail. (Paper 540, Q1)
• Write a note on: Scope of Physical Geography. (Paper 540, Q9-a)

Unit II Questions

• What is insolation? Explain different factors affecting the temperature over the globe by giving examples. (Paper 5072/2292101101, Q3)
• Describe the composition and structure of the atmosphere. (Paper 5072/2292101101, Q4)
• What is insolation? Explain the factors affecting insolation and describe the heat budget of the earth. (Paper 540, Q2)
• Explain the pressure belts and global wind system with suitable diagrams. (Paper 540, Q3)
• Write a note on: Structure of Atmosphere. (Paper 540, Q9-c)

Unit III Questions

• Explain the internal structure of the Earth with reference to seismic evidences. (Paper 5072/2292101101, Q5)
• Define isostasy. Elaborate the isostatic adjustment maintained by the earth. (Paper 5072/2292101101, Q6)
• What is folding? Discuss its various types. (Paper 5072/2292101101, Q7)
• Give a brief account of the internal structure of the earth. (Paper 540, Q4)
• What is isostasy? Explain the views of Airy on isostasy. (Paper 540, Q5)

Unit IV Questions

• What are tides? Explain its types. (Paper 5072/2292101101, Q8)
• What are ocean currents? Describe the factors affecting ocean currents. (Paper 540, Q6)
• Write a note on: Types of Tides. (Paper 540, Q9-b)

Unit V Questions

• "The vegetation distribution over the globe has very large variations." Validate the statement. (Paper 5072/2292101101, Q9)
• Discuss the factors affecting soil formation. (Paper 540, Q7)
• Describe the characteristics of different biomes of the earth. (Paper 540, Q8)

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⚡ Rapid Revision Sheet (Exam-Night Cheat Cards)

One-Line Formula/Concept Recall

• Isostasy: crust floats on mantle in gravitational equilibrium.
• Airy: same density, different thickness (roots).
• Pratt: same depth, different density.
• Insolation factors (mnemonic — "LADLO"): Latitude, Atmospheric transparency, Duration of day, Land-sea distribution, Ocean currents.
• Soil formation (Jenny): S = f(climate, organisms, relief, parent material, time).
• Tide types: Spring = alignment = max range; Neap = right angle = min range.
• Seismic shadow zone (103°–142°): proves liquid outer core.

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Compiled as an exam-ready, unit-wise companion covering 100% of syllabus topics and every question appearing across all three uploaded question papers (Sr. No. 5072, and 540 — both Unique Paper Code 2292101101).