1. Heat Transfer Earth’s atmosphere moves (transfers) heat around in three ways: 1. Radiation (infrared, UV, etc…) The ground or the air can absorb infrared radiation 2. Conduction- a cool object touches a warm object and gets some of its heat
3. Convection- warm liquid or gas moves
around and carries the heat with it

2. The Sun Starts It All
Infrared radiation is absorbed by the ground (or ocean).
The air that touches the ground (or ocean) gets some of its heat- that’s conduction
That same air rises (‘cuz warm air is less dense than cold air) so it carries the heat up with it- that’s convection

3. Remember This Diagram? This whole diagram occurs in the troposphere.
Ground

4. What Other Atmosphere Layers Use Heat Transfer?
Troposphere- uses all three
Stratosphere- the ozone layer absorbs UV radiation, then conducts it to the rest of the stratosphere
Mesosphere- it touches the stratosphere and gets some of its heat by conduction, that heat rises by convection
The thermosphere absorbs infrared radiation directly from the sun
The exosphere absorbs infrared radiation directly from the sun

5. Warm Air Rises, Cool Air Drops
Warm air is less dense (‘cuz the molecules spread out more) so it rises
Cool air is more dense (‘cuz the molecules huddle close together) so it drops
Sound travels faster in warm air (‘cuz warm air moves faster than cold air and the molecules drag of the sound waves with them)