1. Earth’s Changing Atmosphere
Chapter 15

2. Earth’s atmosphere supports life
Atmosphere – a layer of air and gases that surrounds and protects the earth
Keeps Earth warm
Transports energy to different regions
Although important, it is very thin comparatively

3. Atmosphere characteristics
As you go up in the atmosphere (altitude), the air becomes less dense or thinner.
Density is the amount of “stuff” in a certain amount of space ( volume)
The higher you get the less air molecules are between you and the top of the atmosphere.
That means there are less air molecules pushing on you ( less air pressure)

4. A recipe for the atmosphere?
Mostly gases
Some tiny solid or liquid particles
78% nitrogen
21 % oxygen
1% trace gases ( argon, carbon dioxide, etc)

5. Sudden changes in our atmosphere
Volcanic eruptions -lots of gases and ash into the atmosphere in a short period of time.
Forest fires - carbon dioxide, smoke and ash enter the atmosphere
Dust storms - clouds of eroded soil particles enter the atmosphere by strong winds.

6. Energy movement in the atmosphere
Radiation- energy transfer through waves
Conduction - energy transfer by direct contact
Convection –energy transfer by movement of liquid or gas (hot/less dense material rises as cooler/more dense material sinks)

7. Layers of the atmosphere
Troposphere ( closest to the earth)
Stratosphere ( contains the ozone layer)
Mesosphere
Thermosphere

8. Gases in the atmosphere absorb radiation
Certain gases in the atmosphere help protect Earth from ultraviolet and infrared radiation
The Ozone layer is a layer of ozone in the stratosphere that absorbs harmful ultraviolet radiation

9. What keeps the Earth Warm?
A “blanket” of greenhouse gases allows the suns radiation to pass through but then traps some of the reflected heat in.
This process is called the greenhouse effect.