Layers of the Atmosphere

1. Layers of the Atmosphere

2. Troposphere • Ranges from 0 km to 12 km • Lowest layer of the atmosphere • Where we live • Where almost all of the Earth’s weather occurs • “Tropo” means turning or changing; named because conditions are always changing • Shallowest layer of the atmosphere with almost all of the mass of the entire atmosphere • As altitude increases, temperature drops. Why? • Because the air gets less dense as altitude increases.

3. Stratosphere • Ranges from 12 km to 50 km • “Strato” means layer or spreading out • The ozone layer is located in the upper stratosphere, and it protects the Earth by absorbing and filtering out the sun’s harmful U-V rays. • As altitude increases, temperature increases. Why? • The upper stratosphere contains the ozone layer which absorbs energy and turns it into heat causing the temperature to be greater in the upper stratosphere.

4. Mesosphere • Ranges from 50 km to 80 km • Middle layer of the atmosphere • “Meso” means middle • protects the Earth from most meteors • As altitude increases, temperature drops. Why? • The lower mesosphere is closer to the ozone layer (hot) and the air gets less dense with altitude so it gets colder.

5. Thermosphere • Ranges from 80 km and beyond • very thin air • “Thermo” means heat • Broken into 2 layers- The Ionosphere and the Exosphere • As altitude increases, temperature increases. Why? • Although the air is very thin, the molecules are the first to receive energy from the sun, so the molecules are very hot.

6. Ionosphere • Is the lower portion of the Thermosphere • Ranges from 80 km to 550 km • where gas molecules become electrically charged particles called ions • Radio waves bounce off ions and back to Earth • Where the Aurora borealis is found (Northern Lights)

7. Exosphere • Is the outer portion of the Thermosphere • Ranges from 550 km to outer space  • “Exo” means outer • satellites orbit here

8. Temperature Change in the 4 Main Layers