Air

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Detailed Summary

  • Air is one of the most important natural resources. It forms the atmosphere, which surrounds the Earth and makes life possible. Air not only provides oxygen for breathing but also regulates climate, weather, and supports ecosystems.

Composition of Air

  • The atmosphere is a mixture of gases.
    • Nitrogen – 78% (important for plants through nitrogen cycle).
    • Oxygen – 21% (essential for respiration and combustion).
    • Carbon dioxide – 0.03–0.04% (used by plants in photosynthesis).
    • Other gases: Argon, helium, ozone, etc.
    • Water vapour & dust particles are also present.

Structure of the Atmosphere

  • The atmosphere is divided into layers:
    • Troposphere: Lowest layer (up to ~12 km). Contains weather phenomena like rain, clouds, storms.
    • Stratosphere: Contains the ozone layer, which protects life from harmful UV rays.
    • Mesosphere: Coldest layer; meteors burn up here.
    • Thermosphere: Very thin air, auroras occur here.
    • Exosphere: Outermost layer, merges with space.

Importance of Air

  • Provides oxygen for animals and humans.
  • Provides carbon dioxide for photosynthesis.
  • Nitrogen is fixed by bacteria and used by plants.
  • Ozone layer shields us from ultraviolet radiation.
  • Air regulates climate and weather.
  • Winds help in pollination, seed dispersal, and generating wind energy.

Air Pollution

  • Occurs when harmful substances mix with air.
  • Causes:
    • Smoke from industries and vehicles.
    • Burning of fossil fuels (coal, petrol, diesel).
    • Deforestation reducing oxygen.
    • Use of pesticides and chemicals.
  • Major pollutants: Carbon monoxide, sulphur dioxide, nitrogen oxides, chlorofluorocarbons (CFCs), particulate matter.

Effects of Air Pollution

  • Respiratory diseases like asthma and bronchitis.
  • Acid rain (caused by SO₂ and NO₂).
  • Ozone layer depletion (by CFCs).
  • Global warming and climate change (due to greenhouse gases).

Conservation of Air

  • Afforestation to increase oxygen.
  • Reducing use of fossil fuels.
  • Using clean energy sources (solar, wind, hydropower).
  • Using filters in industries and catalytic converters in vehicles.
  • Following international agreements like the Montreal Protocol to protect the ozone layer.