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Clouds, Wind,
and Storms
A Science A–Z Earth Series
Word Count: 1,030
Clouds, Wind,
and Storms
Written by Kira Freed
Visit www.sciencea-z.com
www.sciencea-z.com
Clouds, Wind,
and Storms
Key elements Used in This Book
The Big Idea: Everywhere on Earth, all the time, some type of weather
is occurring. Air masses mix to create clouds, wind, and precipitation.
It may be clear one day but cloudy the next. It can be snowing in one
place while it is warm and sunny elsewhere. Experts are now able
to better predict the weather in advance, giving us information we
need to plan our activities. We often select activities, clothing, and
a place to live based upon weather. Understanding the weather can
also prepare us to take precautions that will keep us safe in the event
of severe weather.
Key words: air pressure, atmosphere, blizzard, cirrus, cloud, cumulus, forecast,
front, gas, hail, hurricane, lightning, liquid, precipitation, rain, sleet, snow, solid,
stratus, temperature, thermometer, thunderstorm, tornado, water vapor, wind
Key comprehension skill: Main idea and details
Other suitable comprehension skills: Compare and contrast; classify information;
cause and effect; identify facts; elements of a genre; interpret graphs, charts,
and diagrams
Key reading strategy: Using a glossary and boldfaced words
Other suitable reading strategies: Connect to prior knowledge; ask and answer
questions; summarize; visualize; using a table of contents and headings
Photo Credits:
Front cover: © iStockphoto.com/David Kay; back cover: © iStockphoto.com/Murat Koc;
title page: © iStockphoto.com/seraficus; page 3: © iStockphoto.com/Nick Carver; page 5 (Sun):
© iCLIPART.com; pages 6 (foreground), 9 (left), 12 (center top, bottom), 13 (center top, center bottom),
18, 22 (bottom): © Jupiterimages Corporation; page 7: © iStockphoto.com/Erdal Bayhan; page 8:
© iStockphoto.com/Mlenny Photography; page 9 (center): © iStockphoto.com/mipan; page 9 (right):
© iStockphoto.com/Kati Molin; page 12 (top): © Digital Vision/Getty Images; page 12 (center bottom):
© iStockphoto.com/Paul Prescott; page 13 (top): courtesy of Ralph F. Kresge/NOAA; page 13 (center):
© iStockphoto.com/Darren Hendley; page 13: © iStockphoto.com/Dave Raboin; pages 19, 21:
courtesy of NOAA; page 20: © Christopher White/123RF; page 22 (top): © iStockphoto.com/
Arturo Limon; page 22 (center): © iStockphoto.com/Xyno
Illustration Credits:
Pages 4, 11, 15: © Learning A–Z
Pages 10, 14, 16: Cende Hill/© Learning A–Z
Written by Kira Freed
www.sciencea-z.com
Clouds, Wind, and Storms
© Learning A–Z
Written by Kira Freed
All rights reserved.
www.sciencea-z.com
Introduction
Somewhere on Earth, almost every
kind of weather is happening right
now. Do you wonder what causes
weather?
Earth is surrounded by a layer of air.
This layer is called the atmosphere.
Table of Contents
Introduction...........................................4
The air may be warm or cold. It may
be dry or wet. Different kinds of air
Wind........................................................6
mix with
Clouds.....................................................9
each other
Precipitation.........................................14
Storms...................................................16
Conclusion...........................................22
Glossary................................................23
all the time.
This causes
wind, clouds,
precipitation,
and storms.
2m
km (37
600
i.) Thermosp
here
m (49.7 mi.) Mesosphere
80 k
.1 mi.) Stratosp
m (21
here
50 k
mi.) Troposp
m (7.5
here
12 k
Atmosphere not to scale
Earth’s atmosphere goes out 600
kilometers (372 mi.) above the
ground. Most weather happens
in the lowest layer.
Index.....................................................24
3
Earth’s Atmosphere
4
The Sun’s energy hits Earth and turns
to heat. The warm ground heats the
air above it. Warm and cool air mix
Wind
Wind is air that moves. We can’t
see it, but we can feel it. We can
to make weather.
see how it moves plants, flags,
Some parts of Earth get more energy
than others. The North and South
and other things.
Air moves because the ground
Poles get less heat than Earth’s
warms air next to it. Warm air is
middle. Dark parts get more heat
lighter than cold air, so it rises. The
than light parts. Parts of Earth also
get more sunlight than others during
different seasons.
cold air above sinks to the ground
because it is heavier. As that cold air
gets warmer, it starts to rise. Then
North: Spring
North: Winter
South: Autumn
South: Summer
Sun
other cold
air takes its
place. All this
North: Summer
North: Autumn
South: Winter
South: Spring
Not to scale
The northern half of Earth is tilted toward the Sun in June, July,
and August, which creates summer. The southern half is tilted
toward the Sun in December, January, and February. While
North Americans and Europeans are enjoying summer, it’s
winter in Australia.
cooler
warm air
cools
cool air
sinks
heating and
cooling of air
makes wind.
5
Moving Air Creates Wind
6
warm air
rises
cool air
warms
warmer
The city
Changes in weather happen when
of Chicago
air of different temperatures meets.
is a good
Did you ever see the lines on a
example of
TV weather map? Those lines
a place where
show where warm and cold air
mixing air
meet. The lines are called fronts.
of different
Chicago’s nickname is the Windy City.
measuring the wind
temperatures
We measure the wind with an anemometer.
Why do people measure the wind? Here are
some reasons.
• Knowing wind speed helps scientists predict
the weather.
• Airplane pilots cannot take off or land if the
wind is blowing
too hard.
• Ship captains
need safe wind
speeds to enter
harbors.
• Machines called
wind turbines turn
strong wind into
electricity. In some
places, the wind
is too calm to use
wind turbines.
makes wind. Chicago is on a lake.
When the Sun shines, the air over
land gets warmer than the air over
water. Warm air over the city rises.
Cool air over the lake moves toward
the land and replaces the warm air
that rose. This causes wind to blow
from the lake to the land. The larger
the temperature difference between
the hot and cold air, the stronger
Wind turbine
the wind.
7
8
Earth’s water changes form all the
time. If water gets very cold, it
freezes and becomes ice. If it gets
warm again, the ice melts. Water
also changes from a liquid to a gas
and back again.
Water (liquid)
Ice (solid)
Water vapor (gas)
When the Sun shines on water, the
Clouds
energy makes some of the water
Clouds are made up of tiny drops
change to water vapor. This water
of water and tiny pieces of ice. They
vapor rises in the air.
are so small and light that they float
in the air.
To understand clouds, first think
about water. Water can take three
forms. We often think about its
liquid form. Water also can be a
solid, called ice. And it can be a gas,
The Sun’s energy makes water evaporate into an invisible gas.
Then this warm, wet air rises, cools, and forms clouds.
called water vapor.
9
10
The Water Cycle
Cloud Type
(Height in Sky)
Description
Forecasting
Cirrus
(High)
condensation
precipitation
evaporation
thin, wispy;
made of ice
crystals
nice weather;
the weather will
change within 24
hours
thin, sheetlike;
cover the whole
sky
come 12–24 hours
before a storm
(either rain or
snow)
gray or bluegray; made of
both ice crystals
and water drops;
usually cover
the whole sky
form in front of
storms (either rain
or snow)
puffy and gray;
form in groups;
made of water
drops
come before a
thunderstorm
surface runoff
soil
ocean
Cirrostratus
(High)
lake
groundwater
The water vapor cools as it rises.
Cool air can’t hold as much water
Altostratus
(Middle)
vapor as warm air. Some of the
water vapor turns back into tiny
drops of liquid water. When these
drops run into each other, they
Altocumulus
(Middle)
make bigger drops. When there are
enough drops, they form a cloud.
Turn the page to see some kinds
of clouds.
11
12
Cloud Type
(Height in Sky)
Description
Stratus
(Low)
Wind and cold temperatures make
solid gray;
usually cover
whole sky
often cause light
mist or drizzle
the water drops and pieces of ice
in clouds bump into each other and
group together. When they get
Stratocumulus
(Low)
puffy and gray;
rarely cause rain,
form in rows with
but they can turn
blue sky between
into rain clouds
them
too big and heavy to stay in the
cloud, they fall to the ground as
precipitation. Rain, snow, hail,
Nimbostratus
(Low)
and sleet are all kinds
light to medium
dark gray blanket
steady rain or
of clouds
snow
Cumulus
(Several Heights)
Cumulonimbus
(Several Heights)
Precipitation
Forecasting
white, puffy;
look like cotton
mean fair weather
but can grow high
like towers and
change into storm
clouds
top of tall
cumulus cloud
that gets
flattened by high
wind
thunderstorm
clouds; can make
heavy rain, hail,
snow, lightning,
and sometimes
tornadoes
13
of precipitation.
Raindrops
aren’t tear
shaped.
They can be
round, oval,
or even
almost flat.
As water droplets in the cloud cool and condense,
they form precipitation.
14
Storms
above
freezing
below
freezing
below
freezing
below
freezing
below
freezing
above
freezing
above
freezing
above
freezing
below
freezing
above
freezing
Storms are extreme weather. As you
read about storms, think about how
air moves and mixes to make them.
Thunderstorms are the most
above
freezing
above
freezing
below
freezing
below
freezing
above
freezing
Rain
Rain
Sleet
Snow
Hail
Key:Snow
Ice
Rain
Hail
common storms. They happen when
warm, wet air hits cold, dry air. The
warm, wet air rises fast to make very
Updraft
tall clouds.
Precipitation depends on air
temperature. If the air between the
cloud and the ground is warm, rain
will fall. But rain that falls through
cold air can turn to sleet. If the air is
very cold in the cloud and below it,
snow will fall. Hail forms when
wind blows ice crystals down and
Warm, moist air rises when it hits cold, dry air. Ice crystals
bump into each other, causing lightning.
up inside a cloud, over and over.
15
16
The worst winter storm is a blizzard.
thuNderstorm safety
Lightning is very dangerous. Follow these tips to
be safe.
• Look for a safe place, such as a building. Never
go under a tree. Lightning strikes the tallest thing
around.
• If you are outside and cannot find a safe place,
crouch down with your head very low. But never
lie down on the ground.
• Stay out of water during a thunderstorm. Do not
touch metal. Water and metal can both carry
electricity.
• Do not use telephones or things that use electricity.
Blizzards have heavy snow and high
winds. They can dump a lot of snow
in a few hours. The snow can bury
cars and trucks. It can block roads.
The wind from the blizzard and
the weight of the snow can knock
out power.
Inside a thunderstorm cloud, small
pieces of ice bump into each other.
The movement makes electricity.
When the cloud fills up with
electricity, lightning happens.
Lightning is very hot. It heats the
air around it. The hot air moves
very fast and makes a strong wave
of air. When the wave reaches your
Driving is very dangerous during a blizzard, especially
on freeways.
ears, you hear thunder.
17
18
Tornadoes are another kind of
extreme weather. They form when
Weather scientists
try to predict
the path of a
hurricane. They
try to warn people
to leave an area
before a hurricane
reaches it. But
hurricanes can
change course
at the last minute.
For this reason, the This shot of Hurricane Ivan (2004)
National Weather was taken by a weather satellite.
Service usually puts
out a hurricane warning only 12 to 18 hours
before it expects a hurricane to reach land.
hot air meets very cold air. When this
happens, the warm, moist air rises
very fast. A strong flow of cold air
moves in to take the place of the
rising warm air. It moves so fast that
it starts to spin. This causes a funnel
cloud to form.
Tornadoes only last a short time.
During warm months, huge areas of
But they can cause great damage.
warm, wet air form over warm parts
of oceans. Cool air moves in to take
the place of the rising warm air. The
air begins to spin, and huge storms
called hurricanes form. High winds
The National Weather Service puts out a tornado
watch when conditions
are right for tornadoes
to form. It puts out
a tornado warning when
a tornado has been seen
or is shown on radar.
and flooding from hurricanes can
Tornadoes have the strongest
winds on Earth.
cause very bad damage.
19
20
Jet st
rea
m
Conclusion
cold, dry air
tornado alley
Colorado
warm, dry air
Scientists know a lot about how kinds
S. Dakota Minnesota
Nebraska
Iowa
of air move and mix together. They
Kansas
L
have many tools to study wind,
Oklahoma
clouds, precipitation, and storms.
Texas
warm, moist air
They use these tools to predict the
The middle of the
United States is nicknamed Tornado Alley.
weather and try to keep people safe.
Tornadoes can form anywhere
But nature is full of surprises! Still, we
in the world. But most tornadoes
can all watch for clues and study the
happen in the United States. This
many kinds of weather in our world.
map shows the kinds of air that
Weather Instruments
meet to make tornadoes.
These tools help scientists predict the weather.
• Thermometers measure temperature.
tornado safety
• Anemometers measure wind speed.
Follow these safety tips during a tornado.
• Go to a basement, if possible. If not, go to a closet
or bathroom. Crouch down under a heavy piece
of furniture or climb inside the bathtub. Cover your
head with your arms.
• If you are outside, lie down in a ditch or a low
place in the ground.
• Stay away from doors and windows.
21
•W
eather vanes and wind socks
measure wind direction.
anemometer
• Barometers measure air pressure.
• Radar detects precipitation.
wind sock
• Airplanes take photographs of clouds.
•S
atellites observe Earth’s weather
from space.
22
satellite
Glossary
precipitationwater that falls from
clouds in the form
of rain, snow, sleet,
or hail (p. 4)
atmosphere a layer of gases
surrounding a planet,
star, or moon (p. 4)
blizzarda severe snowstorm with
cold temperatures, high
winds, and heavy snows
(p. 18)
cloudsvisible groups of water
or ice particles in the
atmosphere from
which rain and other
precipitation can fall (p. 4)
frontlines where two air
masses meet (p. 8)
thunderstormsstorms with thunder,
lightning, heavy
precipitation, and
sometimes hail (p. 16)
tornadoesfast-spinning, funnelshaped clouds that touch
Earth’s surface (p. 20)
water vaporthe gaseous state
of water (p. 9)
windmoving air (p. 4)
Index
hurricanesstrong, spinning
rainstorms with high
winds that start over
an ocean (p. 19)
lightninga flash in the sky made
when electricity passes
from one cloud to another
or between a cloud and
the ground (p. 17)
23
hail, 13–15
ice, 9, 10, 12, 14–17
rain, 12–15
sleet, 14,15
snow, 12–15, 18
Sun, 5, 7, 10
24
thunder, 17
water, 7, 9–12, 14, 17
water cycle, 11