Name _________________________________________
Teacher ___________________________
Weather and Air Pressure
Which heats up faster- land or water?
Air Pressure
The land and water both absorb heat from the Sun,
but land heats up much more quickly. That's why
your toes stay cool when you walk on grass, but burn
on the sidewalk on a hot day!
Even though it is invisible, air has mass. Gravity pulls
air toward Earth's center, just like us. Air pressure
is the weight of air pressing on everything around it.
Air presses equally in all directions—up, down, and
sideways, not just down on them.
Large bodies of water can
absorb a lot of heat without
changing temperature very
much. Ocean temperatures
stay fairly constant
from day to night and
°C
from season to season.
Rock absorbs heat
easily. Its temperature
goes up quickly on
sunny days and cools
off quickly at night.
Warm air rises and
cold air falls toward
Earth’s surface. This
creates convection
currents in the air that
are called winds.
Uneven heating
of the land and
water create
temperature
differences that
make air move.
Warm air
rises
This means that air pressure is greatest near Earth’s
surface at sea level and gets lower as you go up in the
atmosphere.
°C
°F
40
100
40
30
30
80
20
20
60
10
0
°F
50
120
50
10
40
0
100
80
60
40
HOT
Water
Rock & Soil
Greatest air pressure
The density of air molecules is greatest near Earth’s
surface at sea level. Air density gets lower as you go
up in the atmosphere.
Cool air
falls
Wind
HOT LAND
Less air pressure
120
COOL
CONVECTION
Meteorologists use
barometers to measure
air pressure.
Lower in the
atmosphere
Higher in the
atmosphere
or
or
Colder air near
the surface
Warmer air
near the
surface
COOL OCEAN
Higher density
Cold air is more dense
than warm air. Air
always flows from high
pressure areas (denser
air) toward areas of
lower pressure. This
creates winds.
Pre s s u re
Low
High Pressure
Air Mass
Pressu re
Low
The same process also happens on a global scale. The
equator gets the most direct sunlight, so warm air
rises over the equator. Sunlight hits the poles at
an angle, so they are cold. Air cools and sinks at
the poles. Warm air can hold a lot of water vapor.
Air that rises from the carries heat and water vapor
to the cooler poles. This helps even out the Earth's
temperature.
The source of energy for all weather is the Sun,
which heats air and water unevenly.
re
Low P s s u re
When the land is hot and the sea is cool, wind blows
toward the land. This makes a sea breeze. At night
the land cools off, but the sea temperature stays the
same. The wind will blow toward the sea, making a
land breeze.
Lower density
GRADE
SHOW WHAT YOU KNOW!
Weather and Air Pressure
5
DIRECTIONS: Answer these questions without looking at the front page. Check your answers using
the key. If any of your answers are incorrect, go back and reread the information about this topic before
you take the test again.
1
The diagram below shows a landscape
4
Upper atmosphere
Above a continent, a warm air mass slowly
passes over a cold air mass. As the warm air
begins to cool, clouds form. What will most
likely happen next?
A Rain will fall.
B
Hurricanes will form.
C Lightning will strike.
D Hail will form.
5
Which location on Earth receives the most
direct sunlight?
A the deserts
B
Ocean
C the equator
Where in the diagram would the air pressure be
the greatest?
A at the beach
B
on top of the mountain
D the Western Hemisphere
6
C at the bottom of the clouds
D above Earth’s atmosphere
2
B
C water
D hailing
7
D metal
3
B pressure from gamma rays hitting the lower
atmosphere
Polar regions are cold because _.
A the Sun's rays reach the poles at a large angle
B the Sun's rays fall more directly at the poles
C the Sun's rays hit the poles indirectly
Air pressure is the result of _.
A the weight of the lowest layer of the
atmosphere
sunny
C snowing
A rock
soil
A city has a temperature of 75 °F, with partly
cloudy skies. Weather forecasters are predicting
that the air pressure and temperature will drop
during the day. Which type of weather is most
likely for this area in the late afternoon?
A rainy
Which material is able to absorb a large amount
of heat energy without a large increase in
temperature?
B
the South Pole
D Both A and C are true.
8
A student wants to measure air pressure. What
kind of instrument should he use?
C the weight of a column of air pressing down on
an area
A Hygrometer
D All the statements are true
C Barometer
B Anemometer
D Pressurometer
9
The picture below shows a place where air
currents will form due to the uneven heating
of Earth.
13
Which location has the lowest air pressure?
A
A
B
B
C
C
D
D
A
B
C
D
14
In which direction will air currents most likely
move?
A straight down over the land
B
from the land toward the sea
C straight up above the sea
D from the sea toward the land
10
15
The equator has a hot climate because _.
A the Sun's rays reach the equator at a large angle
16
B The molecules in air push in all directions, so
the pressure from above is balanced by
pressure from the sides and pushing up from
below.
C Air pressure is repulsed by the magnetic field
within your body.
D Air pressure is higher near the Earth surface.
C
D
D
A student wants to find out whether water will
get hotter in the sun than in shade. What kind of
instrument should she use?
Energy from the Sun heats Earth unevenly,
causing _.
B air movements that result in changing weather
patterns.
D the layer of gases that surrounds Earth.
A You have the skeleton of a super hero.
C
A global warming.
C the layer of water in the oceans.
The column of air above your head and
shoulders weighs about as much as a car. Why
doesn't the air pressure crush you?
B
D Thermometer
B the layer that contains orbiting space craft.
12
B
C Barometer
D the Earth has more volcanoes near the equator
A the layer in which lithification occurs.
A
B Anemometer
C the Sun's rays hit the equator indirectly
The atmosphere is _.
A
A Hygrometer
B the Sun's rays fall more directly at the equator
11
In the diagram above, location has the lowest
density of air molecules?
C a lack of air movements
D the tilt of the Earth's axis
17
What causes convection currents in the Earth's
atmosphere?
A Uneven heating of the Earth.
B air movements that result in changing weather
patterns.
C a lack of air movements
D the tilt of the Earth's axis
Warmer air
Warmer air
Cooler air
Cooler air
Diagram X
Diagram Y
18
Which of the diagrams above shows formation
of a sea breeze?
A Diagram X.
B Diagram Y.
C Both diagrams show sea breezes.
D Neither diagram shows a sea breeze.
19
Most differences in air pressure are caused by _.
A unequal heating of the atmosphere
B equal heating of the atmosphere
C unequal radiation of the atmosphere
D equal tropospheric discombobulations
20
A
Which of the diagrams below correctly show
how convection currents move in an unevenly
heated liquid?
A
A
B
B
C
C
D
D
B
C
D