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Notes on Earth's Atmosphere

Earth's Atmosphere Overview

  • Definition: Earth's atmosphere is a protective layer of gases surrounding the planet, essential for life.
  • Composition:
    • 78% nitrogen
    • 21% oxygen
    • 1% other gases (argon, carbon dioxide, etc.)

Importance of the Atmosphere

  • Regulates solar energy, affecting climate and weather, and provides breathable oxygen.
  • Shields Earth from harmful UV radiation.
  • Maintains temperatures suitable for life through the greenhouse effect.

Layers of the Atmosphere

  1. Troposphere:

    • Closest layer to Earth.
    • Contains 75% of atmospheric gases.
    • Weather occurs here, with highest density and greatest air pressure.

  2. Stratosphere:

    • Contains the ozone layer which absorbs UV radiation.
    • Less turbulent, allowing planes to fly here.

  3. Mesosphere:

    • Coldest layer (up to -90°C).
    • Burns most meteoroids due to thin air friction.

  4. Thermosphere:

    • Largest layer, absorbs solar radiation.
    • High temperatures but thin air prevents heat sensation.
    • Home to the ionosphere, crucial for radio communications and the auroras.

  5. Exosphere:

    • Outermost layer, extending from about 700 km to 10,000 km.
    • No clear boundary with outer space.

Atmospheric Phenomena

  • Auroras: Display of lights in polar regions caused by solar particles colliding with atmospheric gases.
  • Temperature Gradients: Temperature changes with altitude; generally decreases in the troposphere and increases in the thermosphere.

Summary

  • Earth's atmosphere is vital for sustaining life, influencing weather, and regulating temperatures.
  • Each layer of the atmosphere has distinct characteristics that support different atmospheric phenomena and functions critical for life on Earth.