Layers of the Atmosphere • The layers of our atmosphere are based on temperature changes. • The Troposphere: The Layer in Which We Live The lowest layer of the atmosphere, which lies next to the Earth’s surface, is called the troposphere. • The Stratosphere: Home of the Ozone LayerThe atmospheric layer above the troposphere is called the stratosphere. • The Mesosphere: The Middle Layer The mesosphere is the middle layer of the atmosphere. It is also the coldest layer.
Layers of the Atmosphere, continued • The Thermosphere: The Edge of the Atmosphere The uppermost atmospheric layer is called the thermosphere. • The Ionosphere: Home of the AurorasIn the upper mesosphere and the lower thermosphere, nitrogen and oxygen atoms absorb harmful solar energy. This area is called the ionosphere.
Temperature and the Troposphere • Troposphere: temperature at surface is warmed by the earth absorbing energy from the sun. • Convection currents carry the heat upward, so the air cools as it rises. • The air cools by about 6.5°C for every 1-km above the ground.
Temperature and the Stratosphere • Ozone absorbs ultraviolet radiation from the sun, causing the temperature to increase.
Temperature and the Mesosphere • This layer does not absorb energy from the sun, so it starts to cool again.
Temperature and the Thermosphere • Solar radiation first hits this layer, so the few particles that are here can gain lots of energy. They move rapidly, so they have a very high temperature. • But the air is so thin here that it takes special instruments to measure the temperature accurately.
The Troposphere • Lowest (inner) layer • weather occurs here • we live in it. • “tropo” means turning or changing conditions • depth varies from 9km above the poles to 16km at the equator • shallowest (least thick) layer, but contains most of the mass. • Heated by convection currents
The Stratosphere • “strato” means layer or spreading out • Contains the ozone layer which absorbs energy and causes the temperature to rise • The ozone layer protects the surface from dangerous UV rays • Jet stream
The Mesosphere • Drop in temperature marks beginning of mesosphere • “Meso” means middle • Most meteors burn up here • Coldest layer
The Thermosphere Very top layer Air is very, very thin, about 1/1000th as dense as the air at sea level “Thermo” means heat Extends from 80km to space No definite outer edge Very hot (1800°C), but since air is so thin it would not feel warm at all. Divided into two parts, the ionosphere and the exosphere
The Ionosphere • Energy from sun strips the electrons from the gas molecules creating charged particles called ions. • Radio waves can bounce off of ions, allowing radio waves to travel great distances. • The aurora borealis (Northern Lights) occur here
The Exosphere • “Exo” means outer • Extends for 1000’s of miles • Satellites orbit here • No definite edge