1. The Dynamic EarthSection 2 Objective #9 Describe the layers of the Earth’s atmosphere.

2. The Dynamic EarthSection 2 Composition of the Atmosphere

3. The Dynamic EarthSection 2 Layers of the Atmosphere Based on temp changes The Troposphere The Stratosphere The Mesosphere The Thermosphere

4. The Dynamic EarthSection 2 Layers of the Atmosphere

5. The Dynamic EarthSection 2 The Troposphere The troposphere is the lowest layer of the atmosphere in which temperature drops at a constant rate as altitude increases. This is the part of the atmosphere where weather conditions exist.

6. The Dynamic EarthSection 2 The Stratosphere Temperature rises as altitude increases because ozone in the stratosphere absorbs the sun’s ultraviolet (UV) energy and warms the air. Ozone is a gas molecule that is made up of three oxygen atoms. Because ozone absorbs UV radiation, it reduces the amount of UV radiation that reaches the Earth. UV radiation that does reach Earth can damage living cells.

7. The Dynamic EarthSection 2 The Mesosphere This is the coldest layer of the atmosphere where temperatures have been measured as low as –93ºC.

8. The Dynamic EarthSection 2 The Thermosphere The absorption of X rays and gamma rays by nitrogen and oxygen causes atoms to become electrically charged. Electrically charged atoms are called ions, and the lower thermosphere is called the ionosphere. Ions can radiate energy as light, and these lights often glow in spectacular colors in the night skies near the Earth’s North and South Poles.

9. The Dynamic EarthSection 2 Energy Transfer in the Atmosphere Conduction is the transfer of energy as heat through a material. Convection is the movement of matter due to differences in density that are caused by temperature variations an can result in the transfer of energy as heat.

10. The Dynamic EarthSection 2 Objective #10 Explain The Greenhouse Effect The greenhouse effect is the warming of the surface and lower atmosphere of Earth that occurs when carbon dioxide, water vapor, and other gases in the air absorb and reradiate infrared radiation. Without the greenhouse effect, the Earth would be too cold for life to exist.

11. The Dynamic EarthSection 2 Energy Transfer in the Atmosphere Objective 11: Describe how oceans regulate Earth’s temperature.

12. The Dynamic EarthSection 2 The Greenhouse Effect

13. The Dynamic EarthSection 2 The Greenhouse Effect The gases in the atmosphere that trap and radiate heat are called greenhouse gases. The most abundant greenhouse gases are water vapor, carbon dioxide, methane, and nitrous oxide, although none exist in high concentrations. The quantities of carbon dioxide and methane in the atmosphere vary considerably as a result of natural and industrial processes.