7. This bottle was
photographed at 3600m
(left) then again at sea
level (right)
At sea level, because air
is compressible, the
weight of all that air
above us compresses the
air around us, making it
denser.
We all live underneath a huge ocean of
air that is several miles deep: the
atmosphere.
The pressure on our bodies is about the
same as ten meters of sea water
pressing down on us all the time.
8. Density = Mass / Volume
Warm air is less dense than cool
air. Warm air rises. Cool air sinks.
Air at high altitudes is less
dense than air at lower altitudes.
15. High pressure generally
means fair weather
Air mass in upper
atmosphere
No clouds
Warm, moi
st air
Layer of Air
cannot rise
16. Low pressure generally
means cloudy, rainy
weather
Warm air
Air masses rises, clouds
move apart form
17. High Pressure System: Indicates clear, calm
Weather map conditions with reduced chance of
precipitation. Drier air usually results in a
greater range of high and low temperatures.
Low pressure system: Increased
cloudiness, winds, temperatures, and chance
of precipitation.
18.
19. Measuring Air Pressure
Types of
Barometer
Air Mercury
Barometer
Pressure Aneroid
is measured
by an
instrument
21. High Pressure:
Rising or steady - Continued fair
Slowing falling - Fair
Rapidly falling - Cloudy, Warmer
Medium pressure:
Rising or steady - Same as present
Slowing falling - Little change
Rapidly falling - Precipitation likely
Low Pressure:
Rising or steady - Clearing, cooler
Slowing falling - Precipitation
Rapid falling - Storm
22. Factors Affecting Air Pressure
FACTOR Increase/Decrease Air Pressure
Density
Density
Temperature
Temperature
Water Vapor
Water Vapor
Altitude
Altitude
23. At the top of a mountain How does air pressure
you drank a bottle of affect scuba diving?
water, sealed it, but imploded on your
way down. Why?
A rising barometer A series of hot, humid
indicates a spell of days is preceded by a
cool dry weather. falling barometer.
A southern, coastal areas tend to have Rapidly dropping
lower air pressure than an inland area temperatures are
farther north. accompanied by a
rising barometer.
You are planning a Why would a serious
Picnic and check the athlete decide to train
barometer, which is at a high altitude?
falling. Why should you
cancel the picnic?
You are hiking Mount Everest How does a hot air
and find it hard to breathe at balloon work?
a high altitude.
