1. Chapter 15 The Atmosphere
Page 450

2. The Atmosphere
Thin layer of air that forms a protective covering around the planet!

3. Functions/Benefits Absorbs and traps heat from the sun
Without it, days would be extremely hot & nights would be extremely cold!
Protects life from harmful ultra violet (UV) rays
Provides living things with necessary gases such as oxygen
Transports & Recycles water

4. Properties
Composition
Air Pressure
Relative Humidity
Temperature

5. Composition or Makeup of the Atmosphere
Mixture of gases, solids, & liquids
Extends from the surface of Earth to outer space
Has changed over time!
No oxygen on early earth.
Oxygen began to form from cyanobacteria (tiny photosynthetic microorganisms)
Ozone layer (O3) formed which allowed life to move onto land.

6. Gases in the Atmosphere
Nitrogen (N2) – 78%
Oxygen (O2) – 21%
Water Vapor – 4%
Argon - .93%
Carbon Dioxide - .03%
Trace Elements: Neon, Helium, Methane, Hydrogen gas

7. The Layers of the Atmosphere
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

8. Atmospheric Pressure Gases have mass.
Hundreds of miles of gas above Earth's surface
Earth's gravity pulls the gases toward its surface creating pressure
That pressure is called air pressure!

9. Atmospheric Pressure
Air pressure increases as you get closer to earth.
Which layer has the highest air pressure?

10. Troposphere Directly above the ground (crust)
Extends 11 km or 7 miles up into the air
Contains 75% of the atmospheric gases
Including the oxygen we breath
¾ of the atmospheric mass
Contains the Weather
Gets colder the higher you go
Most of the heat comes from the ground

11. Stratosphere Layer above the troposphere 11 to 50 km (7-31 miles)
Max Temperature = -3oc or 27oF
Contains the Ozone Layer!!!!

12. The Ozone Layer Ozone is comprised of three oxygen molecules (O3)
The ozone layer shields us from UV radiation
UV radiation can damage DNA
So what?

13. Please Save The Ozone Layer!
Ultraviolet radiation can damage DNA
Damage DNA = mutation
Damaged DNA can lead to skin cancer.

14. The Hole in The Ozone Layer
Chlorofluorocarbons (CFCs) used in refrigerators, air conditioners, and aerosols
Destroy Ozone
Hole over Antarctica
Page 472

15. The hole in the ozone was one of the most important problems in the 80s…
Fortunately, most countries banned CFCs by the 1990s due to the Montreal Protocol!

16. The Layers of the Atmosphere
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

17. Mesosphere & Thermosphere
Meso means middle
Thermosphere
Named due to its high temperatures (getting closer to the sun)
Thickest layer  85 to 500 km
Ionosphere – layer of eclectically changed particles (Northern Lights)

18. Changes to the atmosphere
Increased Levels of Carbon dioxide released by burning fossil fuels.
Oil, Natural Gas, & Coal
The greenhouse effect
Increased levels of these gases can cause the earth to get hotter!
Carbon Dioxide
Methane
Nitrogen Oxide
Ozone

19. Air Pollution Smog Air Pollutants
Car exhaust gases & other emissions mix with oxygen in the presence of sunlight
Creates a brown haze
Smoke + Fog
Air Pollutants
Dust (animals, people, dirt)
Soot (burning)
Pollen
Salt (ocean)

20. The Clean Air Act Page 470 1st passes in 1963
Revised many times in order to set stricter standards for air quality & strengthen the government’s ability to enforce regulations.
Measures air quality in an attempt to reduce emission of pollutants that cause health problems such as asthma and cancer.