Layers of the Atmosphere

Earth’s atmosphere is divided into four main layers based upon changes in temperature.

Troposphere Lowest layer of the atmosphere (closest to Earth) You live here Tropo means turning or changing (there is more change in this layer than any other) Weather occurs here Shallowest layer (thinnest) Contains almost all the mass of the atmosphere It is 16 km thick at equator and less than 9 km thick at poles As altitude increases, temperature decreases At the top, temp is about -60 ̊C. Water here forms clouds of ice

Stratosphere Second layer of the atmosphere Reaches from troposphere to about 50 km above surface of Earth Strato means layer or spread out Ozone layer is here (remember it protects living things from ultraviolet radiation from Sun) Jets often fly here because it is calm As altitude increases, temperature increases (because ozone layer absorbs heat)

Mesosphere Third layer Meso means middle Reaches from 50 km to 80 km above Earth’s surface Protects Earth’s surface from being hit by meteoroids (chunks of stone and metal from space – but some still get through) A shooting star is a trail of hot, glowing gases a meteoroid leaves behind in the mesosphere Coldest layer - Temperatures reach – 90 ̊C at the top of the mesosphere As altitude increases, temperature decreases

Thermosphere Outermost layer of our atmosphere Reaches from 80 km above Earth’s surface into outer space. There is no definite upper limit Thermo means heat Thickest layer Hottest layer, temperatures reach up to 1,800 ̊C, but you would not feel warm here (Find out Why?) As altitude increases, temperature increases Has two other layers

Ionosphere Lower layer of the Thermosphere Reaches from about 80 km to 400 km above Earth’s surface Energy from the sun causes gas molecules here to become electrically charged particles Radio waves bounce off ions back to Earth (makes signals travel much farther at night) Auroras happen near the poles because of the ionosphere – these are brilliant streaks of light in night skies

Exosphere Exo means outer Is the outer portion of the thermosphere Reaches from about 400 km outward for thousands of kilometers Space shuttles and satellites orbit Earth here

Remember: Earth’s atmosphere is divided into four main layers based upon changes in temperature and density!!

Why the temperature changes? Troposphere: The air is warmed by heat given off by Earth. The farther away from the surface, the less heat. Stratosphere: Warmed up from the ozone layer absorbing UV rays. Mesosphere: Little ozone to help keep the temperature warm. Thermosphere: High oxygen molecules absorbs light from the sun.

- Layers of the Atmosphere

Temperature Changes The air is warmed by heat given off by Earth. Farther away from the surface, less heat. Warms up from the ozone layer absorbing UV Rays.