What you'll learn
What the atmosphere is made of and how weather works.
Composition
- Roughly 78% nitrogen, 21% oxygen, plus argon, carbon dioxide and water vapour.
- The atmosphere provides oxygen, absorbs harmful radiation and moderates temperature.
Weather
- Weather is short-term; climate is the long-term average.
- Key elements: temperature, precipitation, humidity, wind and pressure.
- The water cycle: evaporation, condensation, precipitation, and the role of the atmosphere in transferring water.
Exam tips
- Distinguish weather from climate clearly.
- Learn approximate percentages of the main gases.
Common mistakes
- Overstating the amount of CO₂ (it is a small fraction).
- Confusing weather with climate.