Download Air Pressure and Wind - Utah Agriculture in the Classroom

Air Pressure and Wind
Utah Science
Purpose
Students will learn about air pressure
and how it affects weather.
Time: 30-45 minutes/activity; one
activity per day for one week
Level: Elementary
Materials
Activity 1
‰‰ Transparency H, “The Effect of
Air Pressure on the Weather”
‰‰ King-sized mattress sheet
‰‰ Paper
‰‰ Scissors
Activity 2
‰‰ 1-liter bottle of quinine or
tonic water (unopened, room
temperature)
‰‰ Transparency 1, “Mercury
Barometer”
Activity 3
‰‰ 9-oz. clean plastic drinking cups
‰‰ Plastic drinking straws
‰‰ Tape
‰‰ Scissors
‰‰ Water
‰‰ Transparency J, “Cape Cod
Weatherglass Barometer”
‰‰ Worksheet 15, “Make a
Weatherglass Barometer”
‰‰ Empty 1-liter plastic soft-drink
bottle
‰‰ Measuring cup
‰‰ Permanent marker
‰‰ Barometer
Activity 4
‰‰ Transparency K, “Aneroid
Barometer”
‰‰ Transparency L, “Weather Maps:
How to Read a Weather Map”
‰‰ Worksheet 16, “How Heavy Is the
Air Today?”
‰‰ Barometer (aneiroid/dry)
Continued on page 2
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Background
The buoyant force acting against our bodies while submerged in an ocean
of air keeps us from feeling its push. At sea level, this overlying air mass exerts
a pressure of 15 pounds per square inch. As air becomes pressurized, it flows
inward, building a mountain of air. Eventually the winds filling this mountain
of air die down, clouds are pushed out or evaporate away, bringing clear skies.
At this point, experts consider this a zone of high pressure. Rising atmospheric
pressure can be caused by two factors, dry, dense (heavy) cold air building
up in regions over the artic and moving southward, or warm moist (highly
pressurized) air building up in warmer locations and moving northward. Both
of these conditions give rise to clear skies, gentle breezes, and fair weather. As
the center slows its rise, it exerts an outward pressure and begins moving great
seas of cold
High
Wind Direction
or warm air
Wind Direction
away from the
regions where
Low
it formed. The
movement
30.23
30.36
30.63 30.24 30.12 30.00 29.88 29.77 29.65 29.53 29.41
9.41 29.43 29.65 29.77 29.88
of these air
Chicago, Illinois
Tulsa, Oklahoma
masses flow in
the direction of least resistance, or lower pressure, bringing a change in wind
direction, wind speed, temperature, clouds, and precipitation.
In the United States, atmospheric pressure is measured in inches of
mercury using a device called a barometer. The term inches of mercury comes
from the linear change in column of mercury which is measured in inches.
This discovery was made in 1634 by a man named Evangelista Torricelli, an
assistant to Galileo. Torricelli discovered that as pressure from the atmosphere
pushed down on a dish of mercury, a corresponding column of mercury
contained in glass and standing in the dish began to rise. Similarly, as the
atmospheric pressure decreased, the corresponding column of mercury fell. A
ruler attached to the column noted the rise and fall of the mercury in inches,
up to a maximum of 32 inches. Since a 32-inch column of mercury is bulky,
aneroid barometers (meaning dry) were eventually created. These instruments
utilize a flexible bellows that’s been tightly sealed after having the air removed.
Increased outside air pressure squeezes the flexible metal; decreased pressure
allows it to expand. It is then attached to a pointer to indicate changes in
pressure on a dial.
During the
1800’s, the Cape Cod
High
Low
Pressure
Weatherglass became
Low pressure
Line
outside lets higher
America’s contribution
pressure inside force
out water
to observing changes in
pressure. This object is a
glass container that holds
water. Contact with the
outside air is shut off by Colored
Water
means of a gooseneck
of glass containing water
How the Cape Cod Glass Works
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1
‰‰ Worksheet 17, “Make a Wind
Vane”
‰‰ Bendable plastic drinking straw
‰‰ 3” square piece of paper
‰‰ 4” X 8” piece of cardboard
‰‰ One ten-penny nail (about 3”
long)
‰‰ Scissors
‰‰ Tape
‰‰ Glue stick
‰‰ Compass
Optional
‰‰ Worksheet 18, “Beaufort Wind
Scale”
‰‰ Worksheet 19, “Wind Chill”
‰‰ “Air Pressure Review Test”
Utah Agriculture in the Classroom
in contact with the
outside air. The battle
of pressure differences
between the outside
air and the inside air
causes the water to rise
or lower, just like the
mercury. Today, varying
zones of pressure
occurring across the
Unites States are
measured in millibars.
[See map.] These
The thin lines on the map are millibars which
millibar readings are
indicate the various zones of pressure across the
standardized by the
United States.
National Weather
Service to “sea-level” values and plotted on surface maps. Because of this, the
reading on your barometer may be less than the National Weather Service’s
reading for our location.
As changes in barometric pressure give way to changes in wind direction
and speed, so too can one expect changes in the weather. Early American
settlers used wind vanes (or wind-fanes) to foretell weather to come. The
word vane comes from the Anglo-Saxon word fane (pronounced “vane” as
in “windvane”), meaning flag. Early weathervanes were often strips of cloth
that wavered from a pole. Since the pioneer farmer knew the direction of east,
west, north and south, there were no markers beneath the vane; this came
later as a reminder for the less informed.
Farmers were especially interested in changes in wind direction, for the
way the wind changed was often as important as the way it was blowing at
the moment, that is, whether it has been backing to the left or veering to the
right as you face the wind. The old saying goes: “A veering wind will clear the
sky. A backing wind says storms are nigh.” Another weathervane saying goes:
“Winds that swing against the sun, And winds that bring the rain are one.
Winds that swing round with the sun, Keep the rain storm on the run.” This
means that a wind that veers in the direction of the sun’s movement (from eat
to west) brings clearing; wind that backs against the sun’s movement brings
storms.
Since then, weather vanes have evolved into metal creatures standing atop
arrows that point in the direction of the wind. Beneath the arrow are letters for
north, south, east, and west. At airports, one can find wind-socks which tell
pilots the direction of winds at the surface of the airfield.
In addition to wind-vanes, an instrument called an anemometer is
used to measure wind speed. Meteorologists use wind speed to calculate a
temperature known as wind chill. Because evaporation is a cooling process,
our skin is sensitive to moisture evaporating from it. In colder temperatures
with high winds, the chill of moisture leaving our skin is compounded by the
chill of the air molecules reaching our skin. In weather forecasts, wind speed
is usually reported in miles per hour, or for ships and aircraft, knots. One knot
is equal to 1.15 m.p.h. In 1806, the Beaufort wind scale was devised by Sir
Francis Beaufort. It originally described the type and amount of sail a ship
should use in a particular wind. Today, the scale describes the effects seen on
land and relates these to wind speeds.
2
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Did you know?
A barometer on an airplane is called
an altimeter. Its measurement of
atmospheric pressure tells the pilot
how high the plane is traveling; the
higher up one flies, the lower the
atmospheric pressure. Jet planes
typically add pressure and oxygen to
the passenger cabin to compensate
for lower oxygen and pressure levels
at higher altitudes.
Looking South
e
E
a st
we s
t
hange and Sun Direc
tion
ind C
. ..
...W
Wind becoming
Wind becoming
easterly brings
westerly brings
POOR WEATHER
FINE WEATHER
W
A ve
sky.
A ba ering wind will clear the igh.
cking w
n
ind says storms are
Talk About the Topic
Review with the group how the buoyant force of air acting against their
bodies is in constant change. Taking a large piece of cardboard or an electric
fan, begin moving the air so the group can feel it. Describe to the group how
you are making wind by causing the air to move. We can feel pressure from
this moving air as it touches our bodies. See if the group can guess which
two conditions are responsible for creating wind in real life. Explain that as
air becomes cold and dense, it begins to move pressing its way into areas of
lighter, warmer air. This typically happens in the winter when large masses of
cold dry air begin to form from the lack of direct sunlight. When these dense
air masses come in contact with warmer, less dense air, movement occurs.
Likewise, as moist air begins to warm and expand from more direct sunlight,
it presses its way into areas of cooler denser air. You can demonstrate this by
blowing up a balloon then releasing it. As the air inside the balloon equalizes
itself with the air around it, movement occurs.
Activity Procedures
Activity 1
1. After discussing the background material, use Transparency H, “The Effect
of Air Pressure on the Weather,” to show students how pressurized air
flows inward, building a mountain of air. Eventually the winds filling this
mountain of air die down, and clouds are pushed away, bringing clear
skies. At this point, this is considered to be a zone of high pressure. As
the center slows it rise, it exerts an outward pressure on the air around
it, moving great seas of dense cold air or warm moist air away from the
region where it was formed. The movement of these air masses flows in
the direction of least resistance, or lower pressure, bringing a change in
wind direction, wind speed, temperature, precipitation, and clouds.
2. Have two people stand in the middle of the group, each person holding
one end of a sheet from a king-sized mattress. Around these two people,
have the rest of the group lie on their stomachs facing inward.
3. Explain that the sheet represents the formation of pressurized air. With the
sheet laying flat on the ground, this represents air at rest.
4. Now have the two members slowly raise the sheet allowing it to rise above
their head creating a domed shape. Explain this is what happens when air
pressurizes from warm moist conditions or cold dry conditions.
5. Quickly, the domed sheet begins to deflate. Point out how his represents a
region of pressurized air on the move.
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6. Repeat the process, but his time, have the group members feel the
difference between the movement of air inflating and deflating the sheet.
Explain that pressurizing air is typically associated with gentler breezes and
fair weather. Likewise, explain that a depressurizing air is associated with
strong winds and stormy weather.
7. Extend this activity by replacing the members with a town of paper
buildings. These buildings can be created using sheets of paper, tape, and
marking pens. See how well the town holds up to changes in pressure. Use
this opportunity to show how rapid changes in pressure, as in the case of
hurricanes, tornadoes, and thunder storms, can cause large amounts of
wind damage. Don’t be surprised if someone in the group figures out that
taping the building to the floor guards against high wind damage.
8. Ask the following questions:
1. Why do stronger winds and storms typically occur in the fall and
spring? (Seasonal changes in light intensity bring about changes in
temperature and moisture.)
2.Where would wind intensity be the greatest? (Close to where the zone
of low pressure exists.)
3. What would contribute to higher winds? (Extreme pressure
differences quickly coming in close contact – tornadoes, hurricanes,
thunderstorms.)
Activity 2
1. Remind them that in an earlier lesson they learned how stratus and
cumulus clouds form during conditions of high moisture and low
temperature (a.k.a. dew point). Similarly, changes in atmospheric pressure
can form similar clouds. As moist air builds up and pressurizes, it begins
to warm, providing little chance for the molecules to condense into cloud
vapor. This can be evidenced by having them blow into their cupped
hands. Explain that as they pressurize the air in their hands, it begins
to warm; hence the reason why we do this to warm our hands in cold
weather. The opposite is true as air depressurizes; air cools down and
molecules condense. This can be evidenced by the fact that when we are
faced with drinking a beverage that is too hot, we often blow on it to cool
it down. This also explains why we appear to exhale steam when the air is
cold. The warm, moist, pressurized air leaving our bodies cools as it comes
in contact with the cooler, lower pressure air outside our bodies. This
change in temperature and pressure causes the moisture to slow down and
condense.
2. U
sing an unopened/room temperature one-liter bottle of clear quinine
or tonic water, pour out a portion of the contents until it is level with the
top of the bottle’s label. (Quinine Water contains particles which improve
condensation.) Explain to the group that the air space in the bottle
represents a low-pressure atmosphere.
3. P
lacing the palm of one hand over the mouth of the bottle, begin to shake
it. Be sure to keep your hand tightly sealed over the top of the bottle.
Explain how the environment inside the bottle now represents a highpressure atmosphere.
4. N
ow release your hand from the bottle to demonstrate what happens
when air loses pressure. As you release your hand, pressure quickly
equalizes with the outside air and a swirl of vapor rises from the bottle.
Explain how swirling masses of clouds often form when air depressurizes.
5. A
sk, How does a fan cool our bodies? (By allowing air to depressurize and
cool; also air movement promotes evaporation which is a cooling process.)
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6. Can the students think of some other examples where vapor is formed
from changing pressure. (Old Faithful Geyser, air escaping from a dryer
vent in winter, a car warming up on a cold winter morning.)
7. Explain that changes in atmospheric pressure are measured using an
instrument called a barometer. In the United States, barometers measure
pressure in inches of mercury. The term inches comes from the linear
change in a column of mercury which is measured in inches. This
discovery was made in 1634 by a man named Evangelista Torricelli, an
assistant to Galileo. Using Transparency I, “Mercury Barometer,” show
them how Torricelli discovered that pressure from the atmosphere pushing
down on a dish of mercury caused a corresponding column of mercury
contained in glass and standing in the dish to rise. Similarly, as the
atmospheric pressure decreased, the corresponding column of mercury
fell. A ruler attached to the column noted the rise and fall of the mercury in
inches, up to a maximum of 32 inches. Activity 3, deals with this concept.
Activity 3
1. Distribute a 9-oz. clear plastic cup and two clear plastic drinking straws to
each group member.
2. H
ave them cut a 4” piece of straw and tape it to the inside of the cup
[Figure 1].
3. Fill the cup half way with water.
4. R
emind them that air is pushing down on the water in their cup and in
their straw. However, the water level in the straw can be raised by blowing
(diverting) the pressurized air away from the straw.
5. U
sing the uncut straw, have them blow across the top of the 4” piece of
straw [Figure 2]. As they blow away the air, pressure from the atmosphere
pushing on the water in the cup pushes the water up the straw, just like
Torricelli’s barometer.
6. A
sk the students if the result would be the same at an altitude of 8,000
feet? (Yes; there is less pressure so you would have to blow less.)
7. E
xplain to the group that this principle was applied to the invention of
the Cape Cod Weatherglass in the early 1800s. Project Transparency
J, “Cape Cod Weatherglass.” This object is a glass container that holds
water. Contact with the outside air is shut off by means of a gooseneck
of glass containing water in contact with the outside air. The battle of
pressure differences between the outside air and the inside air causes the
water to rise or lower, just like the mercury. Using Worksheet 15, “Make
a Weatherglass Barometer,” have them construct their own Cape Cod
Weatherglass.
Activity 3
1. Explain that since the mercury barometer and the Cape Cod Weatherglass
both had their disadvantages, aneroid barometers (meaning dry) were
eventually created. (Project Transparency K, “Aneroid Barometer.”)
Point out how these instruments utilize a flexible bellows that’s been
tightly sealed after having the air removed. Increased outside air pressure
squeezes the flexible metal; decreased pressure allows it to expand. Using
Transparency K, explain how the markings on the liquid barometer are the
same as on the dry barometer. Both measure in inches of mercury and in
millibars. Note that in the United States, barometric pressure is recorded
in millibars but reported in inches of mercury, hence the two reading.
The National Weather Service maintains more than a hundred weather
monitoring sites across the county. These sites record hourly changes in
the weather, including barometric pressure.
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2. Distribute Copies of Worksheet 16, “How Heavy Is the Air Today?,” for
students to complete. Point out how the barometer’s markings associate
clear skies and fair weather with high pressure, and stormy weather with
cloudy skies and low pressure. Show them how to read the barometer,
then take time to have them complete the worksheet.
3. E
xplain that varying zones of pressure occur across the United States and
are measured hourly by stations maintained by the National Weather
Service. These readings are then standardized to “sea-level” values and
plotted on maps. Remember, pressure naturally varies with altitude, which
must be factored out of the reading. Because of this, the reading on your
barometer may be less than the National Weather Service’s reading for
your location. Show Transparency L, “Weather Maps: How to Read a
Weather Map,” to aid in the discussion.
4. E
xplain that as changes in barometric pressure give way to changes in
wind direction and speed, so too can one expect changes in the weather.
Early American settlers used wind vanes (or wind-fanes) to foretell
weather to come. The word vane comes from the Anglo-Saxton word
fane, meaning flag. Early weathervanes were often strips of cloth that
waved from a pole. Farmers were especially interested in changes in wind
direction, for the way the wind changed was often as important as the
way it was blowing at the moment, that is, whether it has been backing to
the left or veering to the right as you face the wind. The old saying goes:
“A veering wind will clear the sky. A backing wind says storms are nigh.”
Another weathervane saying goes: “Winds that swing against the sun, And
winds that bring the rain are one. Winds that swing around with the sun,
Keep the rain storm on the run.” This means that a wind that veers in the
direction of the sun’s movement (from east to west) brings clearing; wind
that backs against the sun’s movement brings storms.
5. Distribute copies of Worksheet 17, “Make a Wind Vane.” From the
worksheet description, have group members build their own wind vane.
Additional Activities
Assign the following worksheets as homework: Worksheet 18, “Beafort wind
scale” and Worksheet 19, “Wind Chill.”
Test students’ comprehension with “Air Pressure Review Test.”
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30.23
30.63
30.24
Tulsa, Oklahoma
30.36
Wind Direction
High
30.12
30.00
29.88
29.77
29.41 29.43 29.65 29.77 29.88
Chicago, Illinois
29.65 29.53 29.41
Low
Wind Direction
Transparency H
The Effect of Air Pressure on the Weather
Transparency I
Mercury Barometer
Inches of
Mercury
32.78
Vacuum
32.48
32.19
Mercury Column
31.89
31.60
Glass Tube
31.30
31.00
30.71
30.42
30.12
29.82
29.53
28.94
28.64
28.35
28.05
27.76
Air Pressure
29.24
27.46
27.17
26.87
26.58
26.28
25.99
Mercury in Dish
Mercury Barometer - The height of the mercury column is a mesasure of
atmospheric pressure.
Colored
Water
High
Low
Low pressure
outside lets higher
pressure inside force
out water
How the Cape Cod Glass Works
Pressure
Line
Transparency J
Cope Cod Weatherglass
Name
Worksheet 15
Make a Weatherglass Barometer
Materials
plastic cup
• 9-oz. clear
s
drinking straw
• two plastic
k bottle
-liter soft-drin
1
ic
st
la
p
ty
p
• em
cup
• measuring
• scissors
marker
• permanent
• tape
Purpose
To show how pressure can be measured
Procedure
1. Cut the two straws in half and tape as shown in Figure 1.
Be sure the straws touch the bottom of the cup.
2. Place 1/3 cup of water in the 9-oz. cup.
3. Place 1/2 cup of water in the one liter bottle.
4. Quickly invert the bottle while inserting it into the cup as
shown.
5. The bottle should stand erect while resting between the
straws.
6. On the outside of the bottle carefully mark the water level.
Be sure to make a thin line so you can see any slight
change in the rise or fall.
Activity
Complete the following chart using your barometer.
Rise or Fall
Day 1
Day 2
Day 3
Day 4
Day 5
Sky Condition
Conclusions by Day 5
Transparency K
Aneroid Barometer
Inc h
29.00
3 29.83 30.1
2
es
of Mer
F
DRY
29
.2
3
.5
29
ry
cu
STO
HA
IN C NGE
R
AI .42 30.71
30
RM
Y
RA
Level System
Aneroid Cell
Atmospheric Pressure in Inches of Mercury and in Millibars.
Inches of
Millibars
Mercury (mb)
32.78
32.48
32.19
31.89
31.60
31.30
31.00
30.71
30.42
30.12
29.82
29.53
29.24
28.94
28.64
28.35
28.05
27.76
27.46
27.17
26.87
26.58
26.28
25.99
25.69
25.40
25.10
1110
1100
1090
1080
1070
1060
1050
1040
1030
1020
1010
1000
990
980
970
960
950
940
930
920
910
900
890
880
870
860
850
1,084 mb (32.01 in.) Highest recorded sea-level pressure:
Agate, Siberia (December 1968)
1,064 mb (31.42 in.) Highest recorded sea-level pressure in
the United States: Miles City, Montana (December 1983)
Strong High Pressure System
1,013.25 mb (29.92 in.) Average sea-level pressure
Deep Low Pressure System
888 mb (26.22 in.) Hurricane Gilbert (September 1988)
870 mb (25.70 in.) Lowest recorded sea-level pressure:
Typhoon Tip (October 1979)
Transparency L
Weather Maps: How to Read a Weather Map
Map 1
Transparency L
Map 2
Name
Worksheet 16
How Heavy Is the Air Today?
A. What barometer readings do the arrows show?
26
27
RA
IN
S
2. 29.80
3. 30.10
4. 30.40
29
30
VE R
YD
CHANGE
31
1. 29.40
5.
IR
FA
4.
RA
IN
RY
B. Draw arrows on this barometer (and number
them) to show the following readings:
3.
Y
RM
O
T
28
VE R
YD
Y
RM
O
T
28
31
(1) (5)
2.
S
(4)
1.
27
(3)
26
(2)
30
IR
FA
29
RY
CHANGE
Name
Worksheet 17
Make a Wind Vane
Materials
straw
lastic drinking
p
le
b
a
d
n
e
b
•1
of paper
• 30” square
of cardboard
• 4" x 8" piece
y nail
• 1 ten-penn
• scissors
• tape
• glue stick
• compass
Purpose
To Determine the wind's direction
Procedure
1. Cut out the template from page two of this worksheet and glue it to your cardboard. The saying
on the template came from early American folklore about wind and weather.
2. Insert a ten-penny nail through the center of the cardboard (where the rooster is on the
template) so the tip is pointing up.
3. Take your plastic drinking straw and bend it in an "L" shape. Slip the slant end of the "L" over
the nail so that the straw swings freely.
4. Cut out the 3-inch square pattern on the second page of this worksheet and fold along the
dotted lines into a triangle.
5. Tape it to the end of the drinking straw as shown in the illustration so that it points in the
direction of the wind.
6. Orient yourself and your wind vane to north using your compass.
Activity
Direction wind is from
Day 1
Day 2
Day 3
Day 4
Day 5
Sky Condition
Conclusions by Day 5
E
Wind becoming
easterly brings
POOR WEATHER
st
ea
4" x 8" template
hange and Sun Directio
A ve
sky.
A ba ering wind will clear the igh.
cking w
ind says storms are n
ind C
W
.
..
Looking South
n...
Wind becoming
westerly brings
FINE WEATHER
we
st
W
Worksheet 17
continued
3" square template
Name
Worksheet 18
Beaufort Wind Scale
Estimating Wind Speed
Observe the wind's effects at the same time of day for a week.
Use the scale to estimate the wind speed. Record the information.
Observation
Smoke goes straight up
Smoke moves, but the wind vane does not
Leaves rustle, wind vane moves, wind felt on face
Leaves and small twigs move, light flag extends
Dust raised, dead leaves and loose paperblow
about, small branches move
Small trees sway, small waves crest on lakes or
streams
Large branches sway, umbrellas difficult to use
Large trees sway, walking against wind is difficult
Twigs break off trees, walking against wind is very
difficult
Branches break off trees, loose bricks blown off
chimneys, shingles blown off roof
Trees snap or are uprooted, considerable damage
to buildings is possible
Widespread damage
Violent destruction
Observation
Day 1
Day 2
Day 3
Day 4
Day 5
Name of Wind
Miles Per Hour
Calm
Light air
Light breeze
Gentle breeze
Moderate breeze
less than 1
1-3
4-7
8-12
13-18
Fresh breeze
19-24
Strong breeze
Moderate gale
Fresh gale
25-31
32-38
39-46
Strong gale
47-54
Whole gale
55-63
Storm
Hurricane
64-73
74 and above
Name of Wind
Miles Per Hour
Name
Worksheet 19
Wind Chill
Wind chill is the combined effect on the human body of air temperature and wind speed.
Wind chill temperatures can give a better idea of how cold it feels than a thermometer reading
alone. Use the chart to answer questions.
Air
temperature
(F)
Wind speed in miles per hour
0
5
10
15
20
25
30
35
40
27
26
50
50
48
Equivalent wind chill temperature (F)
(Pre-2000 Table)
40
36
32
30
28
40
40
37
28
22
18
16
13
11
10
30
30
27
16
9
4
0
-2
-4
-6
20
20
16
4
-5
-10
-15
-18
-20
-21
10
10
6
-9
-18
-25
-29
-33
-35
-37
0
0
-5
-21
-36
-39
-44
-48
-49
-53
-10
-10
-15
-33
-45
-53
-59
-63
-67
-69
-20
-20
-26
-46
-58
-67
-74
-79
-82
-85
-30
-30
-36
-58
-72
-82
-88
-94
-98
-100
-40
-40
-47
-70
-85
-96
-104
-109
-113
-116
A. How cold does it feel when the wind speed is 35 mph and the temperature is 40oF?
o
F
B. How cold does it feel when the wind is 25 mph and the
temperature is 20oF? oF
C. What are the air temperature and wind speed when the
wind chill temperature is -116oF?oF
D. What are the air temperature and wind speed when the
o
wind chill temperature is -9oF?
F
E. How cold does it feel when the wind speed is 30 mph
o
and the temperature is 50oF?
F
F. Currently, what is the air temperature?
o
wind speed?
F
o
wind chill?
F
o
F
Name
Week 4
Air Pressure Review Test
1. Draw a line between each air pressure level and the kind of weather that is likely to follow.
29.98 and falling slowly
Fair
30.06 and rising slowly
Possible rain
29.80 and falling rapidly
Rain
2. Which of the following readings is average sea-level pressure?
A. 27.25
B. 29.92
C. 31.18
3. Give the air pressure reading shown by the arrow on the barometer.
inches
B. inches
CHANGE
C. inches
C.
VE R
YD
27
RA
IN
30
31
Y
RM
O
T
28
A. B.
IR
FA
29
26
A. RY
S
Name
Week 4
Air Pressure Review Test
4. Label points A, B, and C on the air pressure graph shown here using one of the following:
Change
Rain
Clearing
30.10
Barometer Readings
30.00
29.90
29.80
29.70
Time
Date
9 11 1 3 5 7 9 11 1 3 5 7 9 11 1 3 5 7 9 11 1 3 5 7 9 11 1 3 (7:30) A.M.
Jan. 3
Jan. 4
Jan. 5
Jan. 6