1. Atmosphere and Air Pressure
Chapter 1-2a
Atmosphere and Air Pressure

2. Demo
6cm Styrofoam ball (2-1/4 inch) 4 sheets of paper = atmosphere

3. Thickness of the Atmosphere: 70 miles
Scale - Very Thin: 70 / 8000mi (4 / 500 sheets)

4. There is a 70 mile tall column of air above your head!

5. Distribution of Air Molecules
Pressure and Density
Distribution of Air Molecules
90% of all molecules are within 10 miles of the surface
@ 10 miles the pressure is 10x less than surface
99.9% of molecules are within 30 miles of the surface
@30 miles the pressure is 100x less than surface

6. Pressure decreases with Altitude
Ideas about the “edge of the atmosphere”
The Karman Line – air is too thin to support aeronautical flight. Air is so thin that aircraft have to fly so fast to obtain lift that they could leave orbit

7. Layers Based on Temperature
LAYER HEIGHT ABOVE SURFACE
1. Troposphere miles Weather Occurs Here
Other Layers…
2. Stratosphere miles
3. Mesosphere miles
4. Thermosphere miles

9. Functions Warms the Earth – Greenhouse Effect Protects the Earth
Ozone Layer in the Stratosphere absorbs UV
Meteoroids burn in the Mesosphere
Ionosphere in the Thermosphere absorbs X and UV)

10. Function: Warms the Earth

11. Function: Protects from UV

12. Function: Ionosphere Absorbs X and Extreme UV

14. 1-2a Notes Quiz: Atmosphere Name: __________________
What are the Four Layers of the Atmosphere Based on Temperature?
Where is atmospheric Pressure the Greatest?
What layer of the atmosphere has the coldest temperatures?
What layer of the atmosphere has the hottest temperatures?
Why does pressure decrease as we go higher in the atmosphere?
How much does pressure change at the top of the troposphere and stratosphere
What part of the stratosphere absorbs Ultraviolet radiation?
What part of the Thermosphere absorbs X-rays?
How does the Ionosphere affect radio communications?
What is something new you learned today?