1. A “blanket” or “ocean” of air.

2. Layers of the Atmosphere There are 5 layers of the Earth’s Atmosphere: Exosphere (highest)500-???km (>600-190,000) Thermosphere90-500 km Mesosphere50-90 km Stratosphere10-50 km Troposphere (lowest)0-10 km Resources to find properties of these layers include: Your Cat. Events Book – Pages 34-36 Your ScienceSaurus Book – Pages 213-215 The Atmosphere and Ozone Layer BrainPOP Video The Diagrams on the Back of Your Worksheet Research Aid in the classroom Online Research Boundary information varies from source to source and changes daily and seasonally.

3. A Scale Model of the Layers

4. Composition of the Atmosphere Most of the gases came from volcanic eruptions.

5. Where did the oxygen in our atmosphere come from? Oxygen is arguably the most important gas in our atmosphere (for us). Our first atmosphere blew away and our second didn’t have any oxygen for a long time. A primitive type of bacteria called Stromatolies were one of the first to use photosynthesis and produced tons of oxygen.

6. Our Protective Invisible “Force Fields”