6.1 Introduction to the atmosphere

Significant ideas:

  • The atmosphere is a dynamic system that is essential to life on Earth.
  • The behaviour, structure and composition of the atmosphere influence variations in all ecosystems.

Knowledge and understanding:

  1. The atmosphere is a dynamic system (with inputs, outputs, flows and storages) that has undergone changes throughout geological time.
  2. The atmosphere is a predominantly a mixture of nitrogen and oxygen, with smaller amounts of carbon dioxide, argon, water vapour and other trace gases.
  3. Human activities impact atmospheric composition through altering inputs and outputs of the system. Changes in the concentrations of atmospheric gases—such as ozone, carbon dioxide, and water vapour—have significant effects on ecosystems.
  4. Most reactions connected to living systems occur in the inner layers of the atmosphere, which are the troposphere (0–10 km above sea level) and the stratosphere (10–50 km above sea level).
  5. Most clouds form in the troposphere and play an important role in the albedo effect of the planet.
  6. The greenhouse effect of the atmosphere is a natural and necessary phenomenon maintaining suitable temperatures for living systems.

Applications and skills:

  • Discuss the role of the albedo effect from clouds in regulating global average
  • Outline the role of the greenhouse effect in regulating temperature on Earth.


  • Impact to the atmosphere from pollutants can be localized, as evidenced by the destruction of the ozone layer over the poles of the Earth.
  • Pollutants released to the atmosphere are carried by currents in the atmosphere and may create damage in a location other than where they are produced.

Theory of knowledge:

  • The atmosphere is a dynamic system—how should we react when we have evidence that does not fit with an existing theory?


  • Climate change—causes and impacts (7.2)
  • Systems and models (1.2)
  • Introduction to water systems (4.1)
  • Introduction to soil systems (5.1)
  • Biomes, zonation and succession (2.4)
  • Acid deposition (6.4)
  • Climate change—causes and impacts (7.2)