2. Earth’s First Atmosphere 1. NH 3 2. CH 4 3. H 2 O * How did the first atmosphere change into the second atmosphere? Earth’s Second Atmosphere 1. N 2 2. H 2 3. CO 2 4. H 2 O * How did the second atmosphere change into the atmosphere we have today?

3. “Introduction to Weather” I. Earth’s Atmosphere: A. Earth is divided into three areas. 1. Lithosphere -Solid portion of the earth. 2. Hydrosphere -Water portion of the earth. 3. Atmosphere -Gas portion of the earth. II. Composition of the Earth’s Atmosphere: A. What is the earth’s atmosphere made of? 1. 78 % Nitrogen 2. 21 % Oxygen

4. 3. 1 % - 4 % Trace Elements A.) Examples of trace elements are: H 2 O (Solid, Liquid or Gas), CO 2, He, O 3, Methane, Dust and Salt. III Structure of the Earth’s Atmosphere: A. Earth’s Atmosphere has Five Layers: 1. Troposphere: A.) Layer closest to the ground. B.) Nicknamed the “Weather Sphere”. C.) Most dense layer of the atmosphere. ( 75 % of the atmosphere) D.) As you get higher in this layer temperature decreases.

5. 2. Stratosphere: A.) 2nd layer of earth’s atmosphere. B.) The ozone layer is part of this layer. C.) Temperature increases, as you get higher due to the ozone absorbing UV Radiation. D.) The highest large passenger air crafts will fly. 3. Mesosphere: A.) 3rd layer of the atmosphere. B.) Most meteors burn up by the time they leave this layer. C.) As you get higher in this layer temperature decreases.

6. 4. Thermosphere: A.) 4th layer of the atmosphere. B.) T.V. & Radio satellites revolve around earth in this layer. *The ionosphere is a special part of the atmosphere. It is not a separate layer, but part of the thermosphere.the thermosphere Different regions of the ionosphere Different regions of the ionosphere make long distance radio communication possible by reflecting the radio waves back to Earth. It is also home to auroras.radio communication possibleauroras Temperatures in the ionosphere just keep getting hotter as you go up!

7. 5. Exosphere: A.) Outer most layer of the earth’s atmosphere. B.) The space shuttle orbits earth in this layer on most space missions. C.) No clear boundary between this layer and space.

8. IV. Earth’s Ozone Layer: A. What is Ozone? 1. Ozone is a form of oxygen. 2. One atom of oxygen is O, one molecule of breathing oxygen is O 2, and one molecule of ozone is O 3. B. How does the ozone layer help earth? 1. Ozone absorbs most of the ultra violet radiation that enters the earth. 2. Too much exposure to UV radiation can damage most living things. 3. In mammals it WILL! cause CANCER!

9. 4. About 800,000 to 1,000,000 Americans develop skin cancer every year. 5. About 10,000 Americans die every year from skin cancer. C. Is the Ozone Layer Thinning? 1. The ozone layer is thinning and in some areas does not even exist. 2. The biggest hole is over Antarctica. 3. Chlorofluorocarbons or CFC’s are being blamed for thinning most of the ozone layer. 4. CFC’s are made up of 3 Chlorine atoms, 1 Fluorine atom, and 1 Carbon atom. 5. CFC’s are found in refrigerating systems, aerosol cans, and Styrofoam packaging.

10. D. How do CFC’s affect the ozone layer? 1. One chlorine atom, from a CFC molecule, reacts with one of the oxygen atoms, from an ozone molecule. 2. That splits up the ozone molecule into a chlorine oxygen compound and a breathing oxygen molecule. 3. A free oxygen atom can break the bonds of the chlorine oxygen compound. This forms a single chlorine atom and a breathing oxygen molecule. 4. The chlorine atom then will attack another ozone molecule, which will start the process all over again. 5. If we would stop the production of CFC’s right now, it would take Earth’s atmosphere over 50 years to rid itself from CFC’s.