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:
- 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)
- 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
- Mesosphere:
- 50-85 km above Earth’s surface
- Coldest layer, temperatures decrease with altitude
- Meteors burn up in this layer
- 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
- 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.