1. Unit 10 Lesson 2 The Atmosphere Copyright © Houghton Mifflin Harcourt Publishing Company

2. Unit 10 Lesson 2 The Atmosphere Florida Benchmark Copyright © Houghton Mifflin Harcourt Publishing Company SC.6.E.7.9 Describe how the composition and structure of the atmosphere protects life and insulates the planet.

3. Up and Away! Copyright © Houghton Mifflin Harcourt Publishing Company What is Earth’s atmosphere?  The atmosphere is the mixture of gases that surrounds Earth. The functions of the atmosphere include protection from the sun, maintaining temperature, and supplying gases necessary for breathing. Unit 10 Lesson 2 The Atmosphere

4. What is Earth’s atmosphere?  The atmosphere is made of 78 percent nitrogen gas, 21 percent oxygen gas, and 1 percent other gases. The atmosphere also contains small particles of dust, volcanic ash, sea salt, smoke, skin, bacteria, and pollen. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere

5. What is Earth’s atmosphere? In the atmosphere, water is found in the clouds as liquid droplets and solid water in the form of snow and ice crystals. Most water in the air is in the form of water vapor. Water vapor is an invisible gas. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere

6. How do pressure and temperature change in the atmosphere? Gravity pulls gas molecules in the atmosphere toward Earth, causing pressure.  Air pressure is the measure of the force (pressure) with which air molecules push on Earths surface. This is due to the weight of the air. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere

7. How do pressure and temperature change in the atmosphere? As altitude, or distance from Earth’s surface, increases, air pressure decreases. As altitude increases, temperatures change. Some parts of the atmosphere are warmer because of gases that absorb solar energy.  The atmospheres of planets differ in their physical composition. A planet with a cold atmosphere and strong gravity would have the thickest atmosphere. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere

8. Look Way Up Copyright © Houghton Mifflin Harcourt Publishing Company What are the layers of the atmosphere?  The atmosphere is divided into four layers based on temperature and other properties.  The thermosphere is the uppermost layer with temperatures that increase as altitude increases. The thermosphere feels cold because particles are so far apart. Unit 10 Lesson 2 The Atmosphere

9. What are the layers of the atmosphere?  The mesosphere is between the thermosphere and stratosphere. Temperatures decrease as altitude increases.  Meteoroids begin to burn up in the mesosphere. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere

10. What are the layers of the atmosphere?  The stratosphere is between the mesosphere and troposphere. Temperatures generally increase as altitude increases.  The stratosphere is warmer at the top than at the bottom. Ozone in the stratosphere absorbs ultraviolet radiation from the sun, which warms the air. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere

11. What are the layers of the atmosphere?  The troposphere is the lowest layer of the atmosphere. Temperature generally decreases as altitude increases. Temperatures near the surface vary greatly. The troposphere contains 80 percent of the atmosphere’s total mass. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere

12. Here Comes the Sun … Copyright © Houghton Mifflin Harcourt Publishing Company How does the atmosphere protect life on Earth? Earth’s atmosphere reflects or absorbs most of the radiation from the sun.  The ozone layer is in the stratosphere and contains a high concentration of ozone. It absorbs most of the solar radiation.  The ozone layer is what protects life from the suns harmful radiation.  Earth’s atmosphere traps energy from the sun. Earth has moderate temperatures as a direct result of the trapping of energy. Unit 10 Lesson 2 The Atmosphere

13. Here Comes the Sun … Copyright © Houghton Mifflin Harcourt Publishing Company  Clouds trap heat energy which explains why cloudy nights are often warmer than clear nights. Unit 10 Lesson 2 The Atmosphere

14. How does the atmosphere protect life on Earth? Ozone-layer thickness changes by season and location. Scientists have discovered a steady decrease in the overall volume of ozone over time. Ozone can also be destroyed by certain chemicals in the air. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere

15. How does the atmosphere protect life on Earth?  The greenhouse effect is the process by which gases in the atmosphere absorb and radiate energy as heat back to Earth. Shortwave radiation from the sun reaches Earth’s surface and reradiates back into the atmosphere, where it is trapped by greenhouse gases. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 10 Lesson 2 The Atmosphere