1. The Air Around You
Section 15:1

2. Composition of the Atmosphere
Complete the following statement:
The atmosphere consists 78% of what gas?

3. Composition of the Atmosphere
Nitrogen 78%
Oxygen 21% O O

4. Composition of the Atmosphere
Neon
Other gases 1%
Water Vapor
Carbon Dioxide
Helium
Methane
Ozone
Argon
Hydrogen

5. Composition of the Atmosphere

6. Properties of Air Does air have mass?
How can we show that air does have mass?
Watch YouTube video on bhoelzle.wikispaces.com
Video
Egg in bottle

7. Properties of Air Because air has mass it also has
other properties including:
Density =
Mass
Volume
Pressure – force pushing on an area or surface

8. Measuring Air Pressure
Mercury Barometer – glass tube and a
dish of mercury
Pressure is measured by measuring the height of the mercury

9. Measuring Air Pressure
Aneroid Barometer – airtight chamber
connected to a dial by a series of
springs and levers

10. Measuring Air Pressure
Weather reports use several units for pressure
Millimeters of mercury
Inches of mercury
Millibars 1in = 33.87mb

11. Altitude and the Properties of Air
Altitude- Distance above sea level
As altitude increases
Air pressure decreases
Lower
air pressure
There is less weight of air molecules on you as you climb the mountain
Higher
air pressure

12. Altitude and the Properties of Air
As air pressure decreases,
so does density

13. Video