Greenhouse gases and the greenhouse effect
Practice Flashcards
Flip to reveal answersWhat is a greenhouse gas?
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 11 Flashcards — Greenhouse gases and the greenhouse effect
Sign up free to track progress and get spaced-repetition review schedules.
Question
What is a greenhouse gas?
Answer
An atmospheric gas that **absorbs longwave (infrared) radiation** and re-radiates heat, warming the atmosphere — e.g. **CO₂, methane, water vapour**.
Question
What is the greenhouse effect?
Answer
The warming of the atmosphere when **greenhouse gases absorb longwave infrared** radiation that would otherwise escape to space.
Question
What is the enhanced greenhouse effect?
Answer
The **extra warming** caused when humans add **more greenhouse gases** (mainly CO₂) to the atmosphere.
Question
Name the three greenhouse gases you must know.
Answer
**Carbon dioxide (CO₂)**, **methane (CH₄)** and **water vapour**.
Question
Which gas is the main contributor to the ENHANCED greenhouse effect?
Answer
**Carbon dioxide (CO₂)** — mainly from burning fossil fuels.
Question
Which type of radiation do greenhouse gases absorb?
Answer
**Longwave infrared** radiation (the heat re-radiated by the warm Earth) — not incoming visible light.
Question
Why does sunlight still warm the surface if greenhouse gases trap heat?
Answer
Incoming **shortwave** sunlight **passes through** the gases to warm the surface; only the **outgoing longwave infrared** is absorbed.
Question
Give two reasons methane contributes to the greenhouse effect.
Answer
(1) It **absorbs longwave infrared** radiation; (2) per molecule it is a **stronger absorber than CO₂**.
Question
What is the main human source of extra CO₂?
Answer
**Burning fossil fuels** (coal, oil and gas); deforestation also contributes.
Question
How do you explain a positive correlation between CO₂ and temperature on a graph?
Answer
As CO₂ rises, **more longwave infrared is absorbed**, so **less heat escapes** and **temperature rises** — both lines climb together.
Question
Is the natural greenhouse effect harmful?
Answer
No — it keeps Earth **warm enough for life**. Global warming comes from the **enhanced** effect (extra human-added gases).
Read the notes
Full study notes for Greenhouse gases and the greenhouse effect
Topic 4.12 hub
Climate change
More from Topic 4.12
All flashcards in this topic
Biology exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free