APES 4.4 Earth's Atmosphere

Composition

• The atmosphere is a mix of different gases
  • 78% nitrogen
  • 21% oxygen
  • 1% trace gases like argon, Co2, neon, etc.

Layers

• The atmosphere is a blanket of air covering Earth from the ground up
• The exosphere, the highest layer, spans from 600-10,000 km upwards
• The thermosphere is a layer lower, 85-600 km
• Mesosphere, 50-85 km
• Stratosphere, 20-50 km
• Troposphere, 0 to 6-20 km (varies by location)

Temperature Changes

• Air is most dense near the surface
  • The temperature decreases at the top of the troposphere to tropopause (the transition from tropo to strato)
• The stratosphere has a rise in temperature with ozone formation
• Mesosphere temp drops again due to the thinning atmosphere
• Thermosphere receives UV and X-ray radiation, so temp rises again even in extremely thin air