In-Depth Notes on Earth's Atmosphere

ATMOSPHERE

Introduction to Atmosphere

  • The atmosphere is the layer of gases surrounding Earth.
  • Functions of the atmosphere include:
    • Supporting life
    • Absorbing harmful radiation
    • Burning up incoming meteoroids

Meteoroids and their Interaction with the Atmosphere

  • Approximately 25 million meteoroids, micrometeoroids, and other space debris enter Earth's atmosphere daily.
  • This equates to about 15,000 tons of material entering the atmosphere each year.
  • Most meteoroids burn up upon entry, causing them to glow and vaporize.

Composition of Earth's Atmosphere

  • Nitrogen: ~78%
  • Oxygen: ~21%
  • Remaining 1% includes:
    • Argon: 0.93%
    • Carbon Dioxide: 0.04%
    • Varying amounts of water vapour and trace gases.

Layers of the Atmosphere

  1. Troposphere
  2. Stratosphere
  3. Mesosphere
  4. Thermosphere
  5. Exosphere

Basis for Layer Division

  • The layers are divided based primarily on temperature changes with altitude.

Detailed Description of Atmospheric Layers

Troposphere

  • Closest layer to Earth's surface, extending about 12.5 km (7.5 miles) up.
  • Contains 99% of water vapor and is where all weather changes occur.
  • Key Processes:
    • Formation of clouds

Stratosphere

  • Second layer, approximately 50 km above the ground.
  • Houses the ozone layer, protecting Earth from UV radiation.
  • Aircraft fly here due to less turbulence.

Mesosphere

  • Third layer, extending from about 50 km to 85 km above the Earth.
  • Known as the coldest layer; it lacks gases that can absorb heat from the sun.
  • Most meteors burn up in this layer due to friction with thin air, creating "shooting stars".
  • Prevents Earth from being covered in craters, unlike the moon.

Thermosphere

  • Fourth layer, reaching temperatures up to 1800°C (3272°F) due to solar radiation.
  • Contains the ionosphere, comprising electrically charged atoms (ions).
  • Responsible for spectacular light displays, known as auroras:
    • Aurora Borealis in the Northern Hemisphere
    • Aurora Australis in the Southern Hemisphere

Exosphere

  • Outermost layer, located above the thermosphere, ranging from 700 km to 10,000 km above Earth.
  • No clear boundary defined.
  • Home to satellites that facilitate communication, such as television and phone signals.

Conclusion

  • The atmosphere is vital for life on Earth and influences many processes, including weather patterns and protection from space debris.
  • Understanding its layers and composition is crucial for meteorology and environmental sciences.