2. Composition  Nitrogen (N 2 ): 78%  Oxygen (O 2 ): 21%  Other Gases: 1% Argon (Ar): 0.934% Carbon Dioxide (CO 2 ): 0.037% Water Vapor (H 2 O): 0.01 to.04% Neon (Ne): 18.2 ppmv (parts per million by volume) Helium (He): 5.0 ppmv Methane (CH4): 1.8 ppmv Krypton (Kr): 1.1 ppmv Hydrogen (H2): 0.5 ppmv Nitrous Oxide (N 2 O): 0.5 ppmv Xenon (Xe): 0.09 ppmv Ozone (O 3 ): 0.0 to 0.07 ppmv Nitrogen Dioxide (NO 2 ): 0.02 ppmv

3. Pressure  Air Pressure The measure of the force with which the air molecules push on a surface ○ The lower the altitude, the higher the pressure ○ The higher the altitude, the lower the pressure

4. The Atmosphere Layers

5. Troposphere  0-16 km from earth’s surface Top is 10 to 16 km depending on latitude and season.  Temp Range: Highest ever recorded 57.8º C in Libya Coldest ever recorded -89º C in Antartica  Layer right next to the earth’s surface  Most dense 90% of atmospheric mass  Carbon dioxide, water vapor, clouds, air pollution, weather, and life forms are found here  The top of the troposphere is called the tropopause.

8. Stratosphere  From between 10 and 16 to 50 km above Earth’s Surface  Temp Range: -85º C to 0º C  Air is very thin and contains little moisture  Temperature rises with altitude because of ozone (O 3 ) Ozone Layer is found in stratosphere Ozone absorbs solar energy in the form of ultraviolet radiation (warms air, protects Earth’s surface)

10. Mesosphere  50 to 85 km from Earth’s surface  Temp Range: 0º C to -90º C  Temperature gets colder as altitude increases  Meteors are burned up in this layer

12. Thermosphere  85 to 500-1000 km above the Earth’s surface  Temperature can be up to 2000º C in sunlight!  Space Shuttle and ISS (International Space Station) orbit in this layer  What we would think of as “outer space”  Temp increases as altitude increases Absorbs much of Sun’s UV (Ultraviolet) and X-ray energy  Northern Lights (Aurora Borealis) and Southern Lights take place here

14. Exosphere  From between 500-1,000 to 10,000 km (half the distance to the moon)  No clear boundary between exosphere and space  Molecules stay due to the Earth’s gravitational pull  Molecules so few and far between they hardly collide

15. Troposphere Stratosphere Mesosphere Ionosphere Exosphere Thermosphere Write in the labels! Ozone layer