1. Chapter 19:
Earth’s Atmosphere

2. What is in our atmosphere?
78% N2  Cycle, nitrogen-fixed by bacteria in soil to roots, returned via waste & decay
21% O2  Cycle, used by respiration, fires, weathering, returned by photosynthesis
Ozone: O3, absorbs harmful UV radiation, damaged by CFCs & exhaust
1% Ar & other
Particulates: tiny solid or liquid from volcanoes, sea spray, pollen
What is in our atmosphere?

4. Weight of atmosphere pressing down on Earth  air pressure
Pressure decreases w/ altitude
Pressure increases as temperature increases
Pressure decreases as humidity increases b/c water vapor is less dense than air
Measured w / barometer (atm., mm, mb)
Atmospheric Pressure

5. Measuring Air Pressure
Mercurial
Aneroid
Measuring Air Pressure

6. Layers of the Atmosphere
Temperature patterns mark layers
As Altitudes increases, Pressure decreases
Layers of the Atmosphere

7. Layers of the Atmosphere
Troposphere
At surface, weather, almost ½ of all H2O & CO2
Altitude increases, Temperature decreases
Ends in Tropopause (12 km)
Stratosphere
Contains OZONE LAYER
As altitude increases, temperature increases b/c absorbing sun’s energy (UV)
Ends in Stratopause
Layers of the Atmosphere

8. Layers of the Atmosphere cont.
Mesosphere
Temperature decreases as altitude increases
Coldest temperature
Ends with Mesopause
Thermosphere
Highest temperatures b/c of radiation,
O2 & N2 absorbing sun’s energy
Contains IONOSPHERE (Auroras)
Exosphere: entrance into space
Layers of the Atmosphere cont.

10. How does the sun’s energy affect OUR atmosphere?
Electromagnetic Radiation
Energy from sun, travels through space
@ 3 x 10 m/s
Earth heated by energy transfer 8
How does the sun’s energy affect OUR atmosphere?

11. Electromagnetic Radiation
LONGER WAVELENGTHS/LOWER ENERGY
SHORTER WAVELENGTHS/HIGHER ENERGY
Electromagnetic Radiation

12. Upper Atmosphere (U.A.) absorbs almost all radiation except some visible & infrared reach surface
SCATTERING: L.A. deflects radiation in all directions
Absorbed radiation heats surface & emitted as infrared

13. What’s reflected is “ALBEDO”