Hazardous Earth: Revision and Exam Practice

This final lesson brings together everything you have learned across the Hazardous Earth topic. It provides a comprehensive glossary of key terms, revision checklists for each sub-topic, guidance on Edexcel B exam technique, and practice questions with model answer structures. Use this lesson as your go-to revision resource in the weeks and days before your exam.

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Key Terms Glossary

The following table contains all the essential terms you need to know for the Hazardous Earth topic. Being able to define these precisely will earn you marks across all question types.

Term	Definition
Atmospheric circulation	The large-scale movement of air across the Earth's surface, driven by differential heating and the Coriolis effect
Hadley Cell	The largest atmospheric circulation cell, operating between the equator and approximately 30° latitude
Ferrel Cell	The mid-latitude circulation cell, operating between approximately 30° and 60° latitude
Polar Cell	The smallest atmospheric circulation cell, operating between approximately 60° and 90° latitude
Coriolis effect	The deflection of moving objects (including air and water) caused by the Earth's rotation — to the right in the Northern Hemisphere, to the left in the Southern Hemisphere
ITCZ	Inter-Tropical Convergence Zone — a belt of low pressure near the equator where trade winds converge and air rises
Trade winds	Surface winds blowing from the subtropical highs towards the equator (NE in NH, SE in SH)
Thermohaline circulation	The global ocean conveyor belt, driven by differences in water temperature and salinity
Milankovitch cycles	Long-term variations in Earth's orbit (eccentricity, axial tilt, precession) that cause glacial-interglacial cycles
Enhanced greenhouse effect	The additional warming caused by human-produced greenhouse gases trapping more heat in the atmosphere
Mitigation	Actions taken to reduce the causes of climate change (e.g., reducing greenhouse gas emissions)
Adaptation	Actions taken to adjust to the effects of climate change (e.g., building flood defences)
Tropical cyclone	A large, rotating low-pressure weather system with sustained winds ≥119 km/h, fuelled by warm ocean water
Storm surge	A temporary rise in sea level caused by low pressure and onshore winds during a tropical cyclone
Saffir-Simpson scale	A scale classifying tropical cyclones into Categories 1–5 based on sustained wind speed
Tectonic plate	A large, rigid section of the Earth's lithosphere that floats on the semi-molten asthenosphere
Subduction	The process by which a denser oceanic plate is forced beneath a less dense plate at a destructive boundary
Convection currents	Circular flows of semi-molten rock in the mantle, driven by heat from the core, that move tectonic plates
Focus (hypocentre)	The point underground where an earthquake originates
Epicentre	The point on the Earth's surface directly above the focus
Seismic waves	Vibrations of energy released during an earthquake (P-waves, S-waves, surface waves)
Moment magnitude scale	The scale used to measure earthquake energy release; logarithmic (each step = 32× more energy)
Liquefaction	When saturated, loose soil loses its strength during shaking and behaves like a liquid
Tsunami	A series of large ocean waves caused by displacement of the sea floor during a submarine earthquake
Primary effects	Direct impacts caused by a hazard event (e.g., building collapse from ground shaking)
Secondary effects	Indirect impacts resulting from primary effects (e.g., fires caused by ruptured gas pipes)

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Revision Checklists

Use these checklists to ensure you have covered every part of the specification. Tick off each point as you revise it.

Sub-Topic 1: Global Climate

• Explain how the atmosphere redistributes heat energy from equator to poles
• Describe the three-cell model (Hadley, Ferrel, Polar)
• Explain how pressure belts and surface winds are created
• Define and explain the Coriolis effect
• Explain the role of ocean currents (surface and thermohaline) in heat transfer
• Describe evidence for natural climate change (ice cores, tree rings, historical records, sea-floor sediments)
• Explain Milankovitch cycles (eccentricity, axial tilt, precession)
• Explain how volcanic eruptions and solar output affect climate
• Describe the enhanced greenhouse effect and the role of different greenhouse gases
• Present evidence for human-caused climate change
• Explain the impacts of climate change on environments and people
• Compare mitigation and adaptation strategies

Sub-Topic 2: Tropical Cyclones

• List and explain the conditions required for tropical cyclone formation
• Describe the structure of a tropical cyclone (eye, eyewall, spiral rainbands)
• Explain the Saffir-Simpson scale and its limitations
• Describe the global distribution and seasonal patterns of tropical cyclones
• Explain primary hazards (wind, storm surge, rainfall)
• Explain secondary hazards (flooding, landslides, disease)
• Describe factors affecting severity (physical and human)
• Case study: Typhoon Haiyan 2013 — causes, effects, responses
• Case study: Hurricane Sandy 2012 — causes, effects, responses
• Compare Haiyan and Sandy — how development level affects impacts

Sub-Topic 3: Tectonic Hazards

• Describe the internal structure of the Earth (crust, mantle, outer core, inner core)
• Compare oceanic and continental crust
• Explain the evidence for continental drift and plate tectonics
• Explain convection currents, ridge push and slab pull
• Describe all four plate boundary types and their associated hazards
• Give examples for each boundary type
• Explain focus, epicentre and seismic wave types (P, S, surface)
• Compare the Richter and moment magnitude scales
• Explain primary and secondary effects of earthquakes
• Case study: Nepal 2015 — causes, effects, responses
• Case study: L'Aquila 2009 — causes, effects, responses
• Compare Nepal and L'Aquila — how development level affects impacts
• Evaluate prediction, protection and planning for tectonic hazards
• Explain why management differs between HICs and LICs

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Edexcel B Exam Command Words

Understanding command words is essential for answering exam questions correctly. Each command word tells you exactly what the examiner expects: