Download air pressure notes ppt

Air Pressure
Air in the Troposphere
• Air and
density-
• Air particles have mass.
• Particles near ground are
compressed
• More particles squished
together = more m/v = greater
density
• More dense = more collisions
= more pressure
• How is AP
measured?
• With a barometer
• Unit is inches of mercury or
millibars
• How is AP
shown on a
weather
map?
• Lines of equal AP are called
isobars.
• What is the
connection
btwn AP and
altitude?
• Air closer to surface has higher
pressure due to higher density
and more collisions
• Higher up near stratosphere, air
is thin so less density and less
pressure
• **** Avg. sea level pressure =
1013 mb
• On top of Mt. Everest = 300 mb
• What is the
connection
between AP
and
temperature?
• Density as temp.
warm stuff expands
b/c
• Cold air has high density
b/c cold stuff contracts
• Lower density = lower AP =
air rising
• Warmer air will have lower
AP than colder air.
• What is the
connection
btwn AP
and
humidity?
• Moist air is less dense b/c
H2O is light but takes up
lots of space.
• Lower density = lower AP
• If so much
air pressing
on us, why
don’t we
collapse?
• What
happens to a
balloon that
floats up to
upper
atmosphere?
• Our bodies reach
equilibrium b/c not
airtight (holes)
• It would pop b/c air inside
would want to expand
due to less pressure on
outside of balloon.
• How is air
pressure
related to
weather?
• High AP = happy weather, air
is heavy so sinking, so not
rising and forming clouds
• Low AP = lousy weather, air is
light and lifting, so it is rising
and forming clouds
http://www.usatoday.com/weather/tg/whighlow/whighlow.htm