1. Essential Question: What are the characteristics of the Earth’s atmosphere? Science 7

2. Homework: Science Read “The Carbon Cycle” on the wiki Complete homework questions for Tuesday

3. Next Science Test: “Earth’s Atmosphere” Unit Test Monday, September 28 Study guide is also posted online

4. Today’s Topic: What is the atmosphere?

5. Video: Introduction to the Atmosphere

6. Introduction to the Atmosphere: Vocabulary This is the TOTAL collection of ALL the gases that surrounds Earth and helps to maintain and support life. Without this, life could not exist on the planet Earth. ATMOSPHERE

7. Introduction to the Atmosphere: Vocabulary There are three major functions of the atmosphere: To block out harmful radiation from reaching Earth’s surface To keep the planet warm To provide materials necessary for life to exist on Earth (example: oxygen)

8. Introduction to the Atmosphere: Vocabulary There are several properties to remember that FLUID- Because it is a gas, the air in the atmosphere is constantly flowing from one place to another DENSITY- the air in different parts of the atmosphere has different densities (the gas in some parts is more spread out than in other parts) Within a fluid, such as the atmosphere, less dense gases will rise to the top and more dense gases will sink to the bottom

9. Introduction to the Atmosphere: Vocabulary This is the distance or height above sea level of a given location. ALTITUDE (ELEVATION) As the altitude (elevation) of a location in the atmosphere increases, the density of the air in that location DECREASES (gets less dense).

10. Introduction to the Atmosphere: Vocabulary Air Density, Altitude (elevation), and Temperature within the atmosphere have a great effect on one another: As air (and other fluids) HEAT UP, the air EXPANDS (becomes less dense) As air (and other fluids) COOL DOWN, the air CONTRACTS (becomes more dense) As air spreads out, it CONDUCTS heat less efficiently, causing the temperature to drop Therefore, as ALTITUDE INCREASES, AIR DENSITY DECREASES, which causes TEMPERATURE TO DECREASE

11. Composition of the Atmosphere: Vocabulary There are many different gases that make up Earth’s atmopshere. Here are four of them: NITROGEN- the most common gas in the atmosphere; the majority of the atmosphere is made up of this gas OXYGEN- the second most common gas in the atmosphere; it makes up over 20% of Earth’s atmosphere; used by living things as part of respiration CARBON DIOXIDE- this gas makes up less than 1% of the Earth’s atmosphere; it plays an important role in heating the planet WATER VAPOR- this gas makes up less that 1% of the Earth’s atmosphere, though the total amount varies because of the cycling of this substance through its solid and liquid forms; it is necessary for life on Earth

12. Second Video: Composition of the Atmosphere

13. Your Task: Your groups will use the information from your homework, your notes and the videos to complete the diagrams on the “Composition of the Atmosphere” worksheet Your groups may work together

14. Exit Ticket: Access the “Exit Tickets” page of DeBolt’s wiki Click on the link for today’s exit ticket Complete the quiz before leaving class Name format: “your period number, Last name, First name”