1. Ch. 15 section 3 Layers of the Atmosphere troposphere mesosphere ionosphere stratosphere thermosphere exosphere What are the four main layers of the atmosphere? What are the characteristics of each layer?

3. A. Troposphere 1. Earth’s weather occurs here. 2. Depth varies from 16 km to 9 km above the North and South Poles 3. As altitude increases, temperature decreases.

8. B. The Stratosphere 1. 50 kms above Earth’s surface 2. lower stratosphere is -60 c 3. upper stratosphere is warmer 4. middle has more ozone than in the rest of the atmosphere • -ozone absorbs energy from the sun • the energy is converted into heat, • warming the air -protects Earth’s living things from dangers ultra- violet radiation from the sun

13. C. The mesosphere 1. middle layer of the atmosphere 2. between 50-80km above Earth’s surface 3. In the outer mesosphere, temperatures approach -90c. 4. protects Earth’s surface from being hit by most meteoroids

23. D. The Thermosphere 1. air is very thin 2. 80 km above Earth’s surface to space 3. very hot, up to 1,800 C 4. O2 and N2 convert this energy into heat. 5. Divided into two layers: -ionosphere: energy from the sun causes gas molecules to become electrically charged -exosphere: outer portion of the thermosphere