Study notes for quiz on air pressure & wind10/3/2012 10:55:00 PM
Properties (characteristics) of the atmosphere:
atmosphere – a whole layer of air that surrounds Earth
altitude-the distance above sea level
density – the amount of mass in a given volume of a substance
air pressure – the force of molecules pushing on an area.
Temperature- how hot or cold an object is
Altitude
Air becomes thinner as altitude increases; contains less
mass; no definite top to the atmosphere (300 mi becomes
outer space); fewer oxygen molecules to breathe;
measured with an altimeter
Density
Density decreases as you travel upward; air on the top of
mountain is less dense than air at sea level; most of the
mass of the atmosphere is close to Earth’s surface
Air pressure
Air molecules move in all directions, air pressure pushes in
all directions. Air pressure decreases with altitude. The air
molecules in air at sea level are denser than air molecules
in air over a mountain. Air pressure is higher in dense air
than in thin air. Areas of high pressure move to areas of
low pressure. Measured with a barometer.
Temperature Air temperature changes with altitude. Temperature is
warmer at sea level but decreases with altitude in the
mountains. Temperature is measured with a thermometer.
Questions:
What happens to the atmosphere’s density as you travel upward?
The air becomes thinner and less dense.
Why would a climber going to the top of Mt. Everest need an oxygen mask?
There are less oxygen molecules and not enough oxygen to breathe.
Air pressure is related to altitude and what else? density
How do differences in air pressure affect the movement of air?
higher air pressure will move to areas of lower pressure
Notes:
Air becomes less dense as altitude increases.
Differences in density cause air to rise and sink.
The movement of air molecules causes air pressure.
The greater the number of air molecules, the greater the air
pressure.
Air pressure varies in different regions.
When an air molecule bounces off an object, it ___pushes or exerts
force________ on that object.
Why does air pressure push in all directions? air molecules move in all
directions
3. Is the air pressure in a can of tennis balls higher or lower than the air
outside of the can? lower
What would you likely hear when you open this can? A hissing sound
What causes this sound? Air pressure from the outside rushing into the can
4. Air moves along Earth’s surface. What causes this to happen? Uneven
heating and the differences in air pressure
1. Air molecules move constantly and bounce off surfaces, exerting force or
pressure on surfaces.
2. Air pressure decreases as altitude increases.
3. Higher air pressure indicates that air is denser.
4. Air pressure would be higher in the valley because air pressure decreases
as altitude increases.
5. Air will start to move from the area of higher pressure toward the area of
lower pressure.
6. The higher pressure inside the ear pushes the eardrum outward as the
air pressure in the elevator decreases.
Wind Patterns
Term
Definition
Details
Weather
the condition of
Earth’s atmosphere
at a particular time
and place
only found in the
troposphere; wind
is an important part
Wind
air that moves
horizontally, or
parallel to the
ground
difference in
density, difference
in air pressure &
uneven heating
Global wind
winds that travel
caused by uneven
thousands of miles
in steady patterns;
can last for weeks
heating between
the equator and the
north & south poles
(leads to pressure
differences!)
the influence of
Earth’s rotation on
the direction of the
wind
Northern
hemisphere =
winds curve to the
right; Southern
Coriolis effect
hemisphere =
winds curve to the
left
Calm regions
regions where the
wind stays calm in
high & low pressure
Doldrums (lowpressure zone near
the equator)
Horse latitudes
(high-pressure
zone located about
30 degrees north
and south of the
equator)
Wind belts
winds that curve
towards the east or
the west due to the
Coriolis effect
Trade winds (blow
from the east
towards the
equator)
Westerlies (blow
from the west
toward the poles)
Easterlies (blow
from the east
moving from the
poles toward the
mid-latitudes)
Jet stream
Local winds
winds that flow in
the upper
polar jet stream
influences the
troposphere/lower
weather in North
stratosphere from
west to east for
thousands of
kilometers
America
winds that change
daily in a regular
pattern
Sea breeze during
the day (warmer air
rises over land
during the day &
cooler air blows in
from the water.)
Land breeze during
the evening ( cooler
air blows out from
land & warmer air
rises over water at
night.)
Valley breeze
during the day
(flow up the
mountain.)
Mountain breeze
during the evening
( flow down the
mountain.)
Monsoons
winds that change
direction with the
seasons
Winter monsoons
begin over land &
are cool and dry.
Summer monsoons
begin over water &
are moist; they
bring heavy rains.
10/3/2012 10:55:00 PM
10/3/2012 10:55:00 PM