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Air PressureCan you feel it?
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Air Pressure Air pressure is the measure of the force with
which air molecules push on a surface. Air Pressure is
GREATESTat the surface of
Earth because there is more of the
atmosphere above you to push down on you.
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As you move UPthrough the atmosphere,air pressure decreases.
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Air Pressure is dependant on
DENSIT
!ore dense airwill have a hi"herairpressure# there are more air
molecules in a
given space to push down on you
$ess dense airwill have a lowerair pressure#there are fewer air
molecules to push down onyou.
!ore Dense% more particles
to push down on &ou
$ess Dense% fewer particles
to push down on &ou
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Air Pressure is affected by 3 factors
'# Elevation( or altitude
)# Temperature
*# +ater content
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mpact of Elevationon Air Pressure As you move upthrough the
atmosphere, air
pressure decreases.! "here are fewer air molecules above you to
push
down on you, so the force of the air will be less.
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mpact of +ater ,ontent, or
humidit&, on Air Pressure
#oist air is less densethan dry air, and
therefore has a lowerair pressure.
! A water molecule has less mass than other
molecules that ma-e up the air. f you
replace some of the air molecules with water
molecules, the water lowers the density $and
lowers the air pressure%
& '
& '
()&
& ()&
' +ei"hs less since
)/ is li"hter
than Nitro"en and
/0&"en
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mpact of Temperatureon Air Pressure
+arm airis less dense than cold air."herefore, warm air has a
lowerair
pressure and cold air has a hi"herair
pressure.
! The molecules in warm air are movin" fast
and are spread farther apart. "herefore there
are fewer air molecules in a given area to push
down on you.
+arm
Air,old Air
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*arometer
"he piece of e+uipment used to measure
air pressureis a 1arometer
Aneroid *arometer #ercury *arometer
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#ercury *arometer
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Air Pressure Affects the +eather
Air pressure in a weather system reflects the
amount of water in the air, which affects theweather.
$owair pressureusually results in
1adweather stormy,
cloudy, overcast.
i"hair pressureusually results in
Goodweatherclear s-ies, no
precipitation
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Air Pressure on a +eather !ap Areas of (ighand owpressure on
shown
on a weather map with an ( or an .
