S4.14.6 For the adult
The greenhouse effect
The Moon is the same distance from the Sun as the Earth, but it is bitterly cold at night. Why is the Earth warm enough for life?
What this chapter teaches
Sunlight passes through the air and warms the ground. The ground gives out infrared. Greenhouse gases absorb some of it and send part of it back down. This keeps the Earth about 33 °C warmer than it would be. Carbon dioxide, methane and nitrous oxide are the gases that people add. The ozone hole is a separate problem.
Three questions to ask
There is no one right wording. Listen for the idea.
- What passes straight through the air, and what do greenhouse gases absorb?
- Which three greenhouse gases can you name, and where does each come from?
- Why is the hole in the ozone layer not the cause of global warming?
After the chapter, the learner can
- Explain the greenhouse effect with a labelled diagram
- Name the main greenhouse gases and where they come from
What they copy into their notebook
Sunlight passes in. The warm ground gives out infrared. Greenhouse gases absorb it and send some back down. Without this the Earth would be about −18 °C. CO₂, CH₄, N₂O.