Transcript Air Pressure2x

Air Pressure..
Weight of the air pushing around you.
Mercury Barometer
Aneroid Barometer
Density of Air
Dry Air
Moist Air
Which is the most dense ??
Density = mass
volume
Moist Air
Dry Air
N2 = 2 x 14 = 28
17 N2 = 467
12 O2= 384
505
O2= 2 x 16 = 32
H2O = (2 x 1) +16 = 18
12 N2=336
3 O2 = 54
5 H2O = 90
480
Moving Air
Temperature changes result in
pressure changes which make …
Wind
Assume that:
Earth not rotating.
No Coriolis effect
All water
At the poles, cold air
sinks. Dense air
H
falling leads to a
i
high pressure at
g
the surface.
h
Winds blow along the
surface from the poles
to the equator.
Low
Global
Winds
The sun heats the
equator the most.
Hot air rises and
flows toward the
poles. Rising warm air
leads to a low
pressure at the
surface
Lo
w
In reality we find…
Air cools and
sinks long before
it reaches the
poles.
Giving us a six cell
model
Low
High
Add to that the rotation of the
earth..Coriolis Effect
Air flowing Northward from the
equator is bent to the right
We get a global circulation of air
that looks like this…
Polar Northeasterlies
Prevailing Southwesterlies
Prevailing Northeasterlies
-North East Trade Winds
Prevailing Southeasterlies
-South East Trade Winds
Prevailing Northwesterlies
Polar Southeasterlies
•sinking air high pressure
little rain
•Earth’s deserts found here
Horse Latitudes; stuck
here for days falling airno wind
Equator: ITCZ
Inter Tropical Convergence Zone
Hot, Humid, Rain Little or no wind
Doldrums- Sailing hips
stuck here for days rising
air- no wind
The name "horse latitude originated when ships from New England
carrying cargoes of horses sailed through these calm areas. Stranded
between ports without enough wind, their water supplies became
dangerously low. The thirsty crews threw horses overboard because
they didn't have enough water to share. Some of the horses had
already died from thirst.
Horse Latitudes
When the still sea conspires an armor
and her sullen and aborted
currents breed tiny monsters,
true sailing is dead.
Awkward instant
and the first animal is jettisoned,
legs furiously pumping
their stiff green gallop,
and heads bob up
poise
delicate
pause
consent
in mute nostril agony
carefully refined
and sealed over.
- A poem by Jim Morrison, recorded on "Strange Days" by the Doors, 1975.
Small Scale Winds…
Local Winds
Wind comes from the
sea..It’s a sea breeze
Wind comes from the
Land..It’s a Land breeze