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OCR GCSE (9-1) Geography B: Geography for Enquiring Minds (J384) · Spec 1.1a, 1.1b, 1.2a, 1.2b and 1.2c

Global Hazards

Read the notes, then try the questions. Each one is marked the moment you press Check, and shows the right answer and why.

Key ideas

  • Air moves round the world in three cells in each hemisphere: Hadley, Ferrel and Polar. Air rises at the Equator and near 60° (low pressure, cloud, heavy rain). Air sinks near 30° and at the poles (high pressure, dry weather).
  • Sinking air near 30° is why many hot deserts sit close to that latitude.
  • A tropical storm needs warm sea, about 27°C or more. Warm moist air rises, water vapour condenses and releases heat, pressure falls and winds are drawn in. The Coriolis effect makes the storm spin, so storms do not form right on the Equator.
  • Tropical storms weaken over land because they lose the warm, moist air from the sea.
  • The Earth's crust is split into plates. At a constructive margin plates move apart and magma rises. At a destructive margin a denser oceanic plate is subducted. At a conservative margin plates slide past each other.
  • Technology saves lives. Tiltmeters and gas sensors help forecast eruptions. Cross-bracing and base isolators help buildings survive earthquakes.
  • You need two weather hazard case studies (one UK and one outside the UK, both this century) and one tectonic case study. Learn named places, dates, effects and responses.
  • El Nino and La Nina are swings in Pacific Ocean temperatures that change weather patterns across the world, for example bringing drought to some places. They change the odds of a hazard. They are not hazards themselves.

Key terms

Hadley cell
The circulation cell either side of the Equator, where air rises at the Equator and sinks near 30°.
Coriolis effect
The turning of winds caused by the Earth's spin. It makes tropical storms rotate.
Subduction
When a denser plate sinks beneath another plate at a destructive margin.
Focus
The point underground where an earthquake starts.
Primary effect
Damage caused directly by the hazard, such as collapsed buildings.
Secondary effect
Damage that follows from the primary effect, such as fires or a tsunami after an earthquake.

Common mistakes

  • Saying earthquakes at a destructive margin are caused by magma rising. They are caused by plates sticking, then slipping and releasing built-up pressure.
  • Using the wrong type of event. A tectonic event such as an earthquake cannot be your case study for a weather hazard question.
  • Writing about the causes of a hazard when the question asks for its consequences.
  • Treating El Nino and La Nina as hazard case studies. They change weather patterns, and those changes can cause hazards such as drought.

Exam tip

Each Section A topic is worth 13 marks and ends on a levels-marked 6 (once on each paper it is an 8). For a case-study 6, name the place, give the date, and add figures or facts. Say what happened to people, buildings and the economy, then say what was done in response.

Free practice questions

7 questions, 15 marks. Answer, then press Check. The marking guide explains how the marks are worked out. Nothing is saved.

  1. Question 1 · Multiple choice[1 mark]

    What happens to air at the Equator, where the Sun heats the surface most strongly?

  2. Question 2 · Fill the gaps[2 marks]

    Near 30° north and south of the Equator, air ___ and gives ___ pressure.

    Word bank: sinks · rises · low · high

  3. Question 3 · Put in order[1 mark]

    Put the stages of tropical storm formation in order, starting with the warm ocean.

    Use the arrows to put these in the right order, first at the top.

    1. 1The Coriolis effect makes the storm spin
    2. 2Pressure falls and winds are drawn in
    3. 3Warm ocean water heats the air above it
    4. 4Warm, moist air rises
    5. 5Water vapour condenses and releases heat
  4. Question 4 · True or false[4 marks]

    Decide whether each statement about tropical storms is true or false.

    1. The eye of a tropical storm is calm.

    2. Tropical storms weaken when they move over land.

    3. Tropical storms form on the Equator itself.

    4. Tropical storms form all year round anywhere in the tropics.

  5. Question 5 · Matching[3 marks]

    Match each type of plate margin to what happens there.

  6. Question 6 · Fill the gaps[2 marks]

    At a destructive margin, the denser ___ plate is ___ beneath the other plate.

    Word bank: oceanic · subducted · continental

  7. Question 7 · Choose more than one[2 marks]

    Which TWO pieces of technology help scientists forecast a volcanic eruption?

    Choose 2.