Chapter 1-2a

Atmosphere and Air Pressure

Thickness of the Atmosphere:70 miles

Scale - Very Thin: 70 / 8000mi (4 / 500 sheets)

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

Pressure and DensityDistribution 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

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

Layers Based on Temperature

LAYER HEIGHT ABOVE SURFACE

1. Troposphere 0-6 miles Weather Occurs Here

Other Layers…

2. Stratosphere 6-31 miles3. Mesosphere 31- 50 miles4. Thermosphere 51-70 miles

Functions

1. Warms the Earth – Greenhouse Effect

2. Protects the Earth • Ozone Layer in the Stratosphere absorbs UV• Meteoroids burn in the Mesosphere• Ionosphere in the Thermosphere absorbs X and UV)

Function: Warms the Earth

Function: Protects from UV

Function: Ionosphere Absorbs X and Extreme UV

1-2a Notes Quiz: Atmosphere Name: __________________

1. What are the Four Layers of the Atmosphere Based on Temperature?

2. Where is atmospheric Pressure the Greatest?

3. What layer of the atmosphere has the coldest temperatures?

4. What layer of the atmosphere has the hottest temperatures?

5. Why does pressure decrease as we go higher in the atmosphere?

6. How much does pressure change at the top of the troposphere and stratosphere

7. What part of the stratosphere absorbs Ultraviolet radiation?

8. What part of the Thermosphere absorbs X-rays?

9. How does the Ionosphere affect radio communications?

10. What is something new you learned today?