Pearson Edexcel GCSE (9-1) Geography B (1GB0) · Spec 1.1, 1.2 and 1.3
Global circulation and climate change
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 rises at the Equator, where the Sun heats the ground most. Rising air cools and condenses, so there is low pressure and heavy rain. This is why tropical rainforests grow there.
- Air sinks near 30 degrees north and south. Sinking air gives high pressure and dry, cloudless weather. This is where many hot deserts are.
- The circulation has three cells in each hemisphere: the Hadley cell (0 to 30 degrees), the Ferrel cell (30 to 60 degrees) and the polar cell (60 to 90 degrees). Surface winds blow from high pressure to low pressure.
- Climate has changed naturally for millions of years. Evidence includes ice cores, tree rings, pollen and written records. Natural causes include volcanic ash and changes in the Sun's output and the Earth's orbit.
- Human causes add to the greenhouse effect: burning fossil fuels releases carbon dioxide, and farming cattle releases methane.
Key terms
- Greenhouse effect
- Gases such as carbon dioxide and methane absorb heat leaving the Earth and trap it in the atmosphere.
- Ice core
- A tube of ice drilled from an ice sheet. Air bubbles trapped in it show what the atmosphere was like long ago.
- Pollen record
- Pollen preserved in mud and peat. It shows which plants grew, and so what the climate was like.
- Hadley cell
- The circulation cell between the Equator and about 30 degrees north or south.
- Fossil fuel
- Coal, oil or natural gas. Burning it releases carbon dioxide.
Common mistakes
- Saying sinking air makes low pressure. It makes high pressure. Rising air makes low pressure.
- Counting human-made warming as evidence of natural climate change. Evidence of natural change is the past record, such as ice cores, tree rings and pollen.
- Thinking greenhouse gases make their own heat. They absorb heat leaving the Earth and trap it.
Exam tip
Section A of Paper 1 ends with an 8-mark Assess or Evaluate question (AO2 4 + AO3 4). If the question asks you to assess a view, such as human causes outweighing natural ones, write about both sides and then give a verdict. A 2-mark Explain one question needs a point and a development of that same point.
Free practice questions
7 questions, 17 marks. Answer, then press Check. The marking guide explains how the marks are worked out. Nothing is saved.
- Question 1 · Multiple choice[1 mark]
Air sinks near 30° north and south of the Equator. What does this cause at the surface?
- 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
- Question 3 · True or false[4 marks]
Decide whether each statement about air pressure and winds is true or false.
1. Surface winds blow from high pressure to low pressure.
2. Trade winds blow from about 30° towards the Equator.
3. Sinking air creates low pressure at the surface.
4. The Equator is labelled 0° because it is the coldest place.
- Question 4 · Matching[4 marks]
Match each feature of global atmospheric circulation to its description.
- Question 5 · Fill the gaps[2 marks]
Burning ___ fuels releases carbon dioxide, which strengthens the ___ effect.
Word bank: ozone · fossil · greenhouse
- Question 6 · Sort into groups[3 marks]
Sort each cause of climate change into natural or human.
Volcanic eruptions
Changes in the Earth's orbit
Burning coal for electricity
- Question 7 · Multiple choice[1 mark]
Which of these is evidence of natural climate change in the past?