Atmospheric Composition and Structure

Atmospheric Composition

  • Primarily composed of:
    • Nitrogen (N2): 78%
    • Oxygen (O2): 21%
    • Argon (Ar): 0.9%
  • Trace gases:
    • Carbon Dioxide (CO2): 0.04% (increasing due to human activities)
    • Water Vapor (H2O): Variable, crucial for weather patterns
    • Methane (CH4), Nitrous Oxide (N2O), Ozone (O3): Greenhouse gases that trap heat
    • Other trace gases: Neon, Helium, Krypton, Xenon

Atmospheric Structure

The atmosphere is divided into several distinct layers based on temperature variations:

  1. Troposphere:
    • Lowest layer (0-10 km)
    • Contains most of the atmosphere’s mass and water vapor
    • Temperature decreases with altitude
    • Where weather occurs (clouds, rain, storms)
  2. Stratosphere:
    • 10-50 km above Earth’s surface
    • Contains the ozone layer, which absorbs harmful UV radiation
    • Temperature increases with altitude due to ozone absorption
  3. Mesosphere:
    • 50-85 km above Earth’s surface
    • Coldest layer, temperatures decrease with altitude
    • Meteors burn up in this layer
  4. Thermosphere:
    • 85-600 km above Earth’s surface
    • Temperatures increase dramatically due to absorption of solar radiation
    • Contains the ionosphere, where charged particles interact with solar radiation
  5. Exosphere:
    • Outermost layer, gradually merging with outer space
    • Very low density, molecules can escape into space

Key Points:

  • The atmosphere is essential for life on Earth, providing breathable air, protecting us from harmful radiation, and regulating temperature.
  • The composition and structure of the atmosphere play crucial roles in Earth’s climate and weather patterns.
  • Human activities, such as the burning of fossil fuels, are altering the composition of the atmosphere, leading to climate change.

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