Chapter 1 Earth: The Water Planet

```Chapter 1
The Atmosphere
Section 3
Air Pressure
Properties of Matter
• All matter in the universe has:
– Mass
– Volume
– Density
– Pressure
Is air matter?
How Do We Find Out If Air
Has Mass and Volume?
If you put that balloon filled
with air onto a triple beam
balance, would the mass
get bigger by the tiniest
amount or would it stay the
same?
It gets bigger…
THAT’S MASS!!!
As you breathe into a
balloon, does it grow or just
stay the same size?
It gets bigger…
THAT’S
VOLUME!!!
Properties of Air
• Because air has mass and volume, we can find
air’s density because
Density = mass/volume
Is Air Matter?
• Air has…
–Mass
–Volume
–Density
–Pressure
Put air in a balloon on a triple beam balance
Put air in a balloon and measure the size
Density = mass ÷ volume
Have you heard about “air pressure” before?
Properties of Air
• The force pushing on an area or surface is
known as pressure.
• Air pressure is the result of the weight of a
column of air pushing down on an area.
Properties of Air
Measuring Air Pressure
• A barometer is an instrument that is used to
measure changes in air pressure.
• There are two kinds of barometers: a mercury
barometer uses liquid, while an aneroid
barometer uses springs and levers.
Measuring Air Pressure
Increasing Altitude
• As you increase in
altitude (go higher
up), the air pressure
and air density
decrease because
the amount of air
above you gets less
and less and is more