2.1 Energy in the Atmosphere

1. 2.1 Energy in the Atmosphere p. 42 - 45

2. Guide for Reading • In what form does energy from the sun travel to Earth? • What happens to energy from the sun when it reaches Earth? • Which color of visible light has the longest wavelength? • Why would particles from volcanic eruptions make sunsets and sunrises more red?

3. Energy from the Sun • Energy travels to Earth as electromagnetic waves • Form of energy that can travel through space • Classified according to wavelength • The direct transfer of energy by electromagnetic waves is called radiation

4. Energy from the Sun • Most of the energy from the sun reaches Earth in the form of visible light and infrared radiation, and a small amount of ultraviolet light.

6. Energy from the Sun • Infrared radiation is a form of energy with wavelengths that are longer than red light. • Not visible • Can be felt as heat • Example: lamps used to keep food warm in restaurants give off both visible red light and invisible infrared light

7. Energy from the Sun • The sun also gives off ultraviolet radiation, which has wavelengths that are shorter than violet light. • Cause sunburns • Can cause skin cancer and eye damage

8. Energy in the Atmosphere • When the rays of the sun pass through the atmosphere, some of the energy from the sun is absorbed within the atmosphere • Some infrared radiation is absorbed by water vapor and carbon dioxide • The ozone layer in the atmosphere absorbs most of the ultraviolet radiation • Clouds, dust and other gases also absorb energy from the sun

9. Energy in the Atmosphere • Some sun rays are reflect • Clouds act like mirrors, reflecting some solar energy back into space • Dust particles and molecules of gases in the atmosphere reflect light from the sun in all directions

10. Energy in the Atmosphere • Reflecting of light in all directions is called scattering • When you look in the sky, the light you see has been scattered by gas molecules in the atmosphere • Gas molecules scatter short wavelengths of visible light more than longer wavelengths • Why the sky is blue!

11. Energy in the Atmosphere • When the sun is rising and setting • Light form the sun passes through a thicker part of the atmosphere • More light from the blue end of the spectrum is removed by scattering • The remaining light from the sun contains mostly red and orange light

12. Energy at Earth’s Surface • Some of the sun’s energy reaches Earth’s surface and is reflected back into the atmosphere • Some is absorbed by the land and water and changed into heat

13. Energy at Earth’s Surface • When Earth’s surface is heated, it radiates some of the energy back into the atmosphere as infrared radiation. • The IR cannot travel all the way through the atmosphere back to space • Absorbed by water vapor, carbon dioxide, methane, and other gases

14. Energy at Earth’s Surface • Absorbed radiation heats the gases in the air and a “blanket” around earth is formed • Holds heat in the atmosphere • The process by which gases hole heat in the air is called the greenhouse effect. • Keeps Earth’s temperature comfortable for most living things