Download The Water Cycle - Jackson School District

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ISBN 0-15-362044-7
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Lesson 1
What Is the Water Cycle? . . . . . . . . . . . . . . . . . . . .2
Lesson 2
How Is the Water Cycle Related to Weather? . . .10
Lesson 3
How Do Land Features Affect the
Water Cycle? . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Lesson 4
How Can Weather Be Predicted? . . . . . . . . . . . . .24
VOCABULARY
water cycle
precipitation
evaporation
condensation
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The water cycle is the endless movement of water from
Earth into the air and then back to Earth.
2
Precipitation is water
that falls from clouds
to Earth. Precipitation
is rain, snow, sleet, or
hail.
Evaporation is the
change of a liquid to a
gas. Water evaporates
into a gas called water
vapor.
Condensation is the change of a gas to a liquid.
Water vapor condenses to water. Condensed water
can form clouds.
Reading Focus Skill
SEQUENCE
A sequence is the order in which things happen.
Look for the sequence in which water changes
during the water cycle.
The Water Cycle
The water cycle is the endless movement of water
from Earth into the air and back to Earth. As the sun
warms Earth, water changes to water vapor. Water vapor,
a gas, goes up into the air. If water vapor cools, it changes
back to a liquid and falls to Earth as precipitation.
Precipitation is rain, snow, sleet, or hail. The sun changes
precipitation to water vapor again, and so the water cycle
continues.
What happens after water
vapor turns back to a liquid?
Water vapor cools,
changes to liquid,
and forms clouds.
Water changes to
water vapor.
Water falls back
to Earth as
precipitation.
Precipitation soaks
into the ground and
flows into streams,
rivers, lakes, and
the ocean.
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What happens to a puddle of water after the sun
comes out? The water changes from a liquid to a gas,
called water vapor. This change is called evaporation.
Water evaporates from oceans, lakes, and rivers. Water
evaporates from soil. It even evaporates from your skin
as you sweat. The water vapor then mixes with other
gases in the air. It moves as the wind blows.
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A Closer Look at the
Water Cycle
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6
The water vapor moves up into the air. It cools. As it
cools, it changes into liquid water. This change from
gas to liquid is called condensation. These tiny drops
of water collect on bits of dust. The drops of water form
clouds. Inside a cloud, tiny drops join to make bigger
drops. When the drops are heavy enough, they fall to
Earth as precipitation.
Tell what must happen before it begins to rain.
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7
Runoff and Groundwater
When rain falls, some water soaks into the soil. Plants
use much of this water. Some water evaporates, too. But
some water moves deep down into the ground until it
gets to solid rock. Water cannot move through the rock,
so it collects there. This underground water is called
groundwater.
B Some precipitation becomes groundwater.
Some becomes runoff.
A Flowing water from melted snow.
Rain that does not soak into the ground can become
runoff. Runoff flows into creeks and streams. Creeks and
streams flow into rivers. Some rivers flow into the ocean.
Tell the order in which rain becomes
groundwater.
Review
Complete these sequence sentences.
1.When water on Earth is heated by the sun, it
changes to a gas called _______.
2.When water vapor cools, it changes to a liquid
and falls back to Earth as _______.
3.When condensation happens, water changes
from a _______ to a liquid.
4.When rain falls and collects deep in the
ground above rock, it becomes _______.
VOCABULARY
VOCABULARY
rain
sleet
snow
hail
tornado
hurricane
How Is the
Water Cycle
Related to
Weather?
Rain is liquid water.
Rain forms and falls
when air temperature is
higher than 0°C.
10
Sleet is frozen rain.
Sleet forms when rain
falls through freezing
air and turns to ice.
Snow is made of ice
crystals. Snow forms
when the air temperature is so cold that
water vapor changes
directly into ice.
Hail is round pieces
of ice. It forms when
frozen raindrops
become coated with
layers of water that
freeze.
A tornado is a fastspinning wind that
stretches from storm
clouds to the ground.
A hurricane is a large
tropical storm with wind
speeds of 119 kilometers
per hour or more.
11
Reading Focus Skill
cause and effect
A cause is what makes something happen. An effect
is what happens.
Look for the causes of different kinds of weather.
Kinds of Precipitation
Rain, sleet, snow, and hail are kinds of precipitation.
Precipitation is part of the water cycle.
Rain is liquid water. It forms from water vapor that
condenses in the air. Rain falls if the air temperature is
above 0°C (32°F).
Sleet is frozen rain. It forms when rain falls through
freezing air and turns to ice. It can also form in clouds.
Rain B
Sleet A
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Snow is made of ice crystals. It forms when the air
temperature is so cold that water vapor changes directly
to ice.
Hail is round pieces of ice. It forms when rain freezes
and falls to warmer air. There, more rain coats the frozen
rain. Wind then carries it back up to colder air. The
coating freezes. This happens over and over until hail
becomes too heavy. Then it falls to the ground.
Explain what causes hail to form.
Snow B
Hail B
13
Severe Storms
Heat from the sun powers the water cycle. It is the same
energy that causes severe storms.
Thunderstorms are severe storms with lightning, strong
winds, and heavy rain. Sometimes tornadoes form during
thunderstorms. A tornado is a fast-spinning wind that
stretches from the clouds to the ground. Winds can reach
speeds of 400 kilometers (250 mi) per hour or more.
Blizzards are severe snowstorms. Heavy snowfall, strong
winds, and low temperatures can last for hours.
D Tornado
Blizzard B
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9/26/07 9:53:34 PM
A hurricane is a large tropical storm with wind speeds
of 119 kilometers (74 mi) per hour or more. A hurricane
forms over warm ocean water. Its center is called the
“eye.” Winds spin around the eye. Heavy rain and huge
waves can cause flooding on land.
What causes all severe storms?
Hurricanes are categorized by their wind speed. B
Hurricane Strength
Category/Wind Speed
Hurricanes
5 (>155 mph)
Hurricane Andrew, 1992
4 (131–155 mph)
Hurricane Charley, 2004
3 (111–130 mph)
Hurricane Betsy, 1965
2 (96–110 mph)
Hurricane Floyd, 1999
1 (74–95 mph)
Hurricane Agnes, 1972
15
Weather Safety
Severe storms are dangerous. Strong winds and hail
can damage property. Downed power lines and trees
can cause injuries. Heavy rains and waves can cause
flooding. Heavy snow and very low temperatures can
make it dangerous to be outside.
BHeavy rains have flooded this area.
B Flood
16
What can you do to stay safe in severe weather? Listen
to local radio and TV stations. They give updates and
directions. Stay inside unless officials tell you to leave.
Know where to go and how to get there in case you
must leave quickly. If your community has weather sirens,
pay attention when they go off. Know what to do.
Tell how a severe storm might affect
you, and what you would do.
Hurricane
warning flags C
A Weather
siren
Review
Complete these cause and effect statements.
1.When rain falls through freezing air and turns
to ice, _______ forms.
2.When water vapor changes directly into ice,
_______ forms.
3.Heavy rain from a hurricane can cause _______
on land.
4.When a fast-spinning wind stretches from the
clouds to the ground, a _______ forms.
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VOCABULARY
VOCABULARY
sea breeze
land breeze
rain shadow
How Do
Land Features
Affect the
Water Cycle?
A sea breeze is a cool breeze that moves from
the sea to the land. It usually happens during
the day when the sea is cooler than the land.
18
A land breeze is a cool breeze that moves
from the land to the sea. It usually happens
at night when the land is cooler than the sea.
wet side (up)
dry side (down)
A rain shadow is the area on the downwind
side of a mountain with less rain and clouds.
19
Reading Focus Skill
cause and effect
A cause is what makes something happen. An effect
is what happens.
Look for the effects of landforms on the water cycle.
Sea Breezes and Land Breezes
Land heats up and cools down faster than water. This
makes the temperature of air over land different from
the temperature of air over water.
During the day, air over water is cooler than air over
land. The cooler air moves toward land. It pushes the
warmer air upward. This causes a sea breeze. A sea
breeze is a breeze moving from the sea to the land.
B Sea breeze
20
At night, air over land is cooler than air over
water. The cooler air moves toward the water. It
pushes the warmer air upward. This causes a land
breeze. A land breeze is a breeze moving from
the land to the sea.
Explain what causes a sea breeze.
B Land breeze
21
Sea-Breeze Storms
When water vapor cools, it condenses to form
precipitation. Sometimes, cool sea breezes push clouds
toward the land. The clouds then produce storms over
the land. These storms are called sea-breeze storms.
Florida is a peninsula, land with water on three sides.
Sea breezes can come from two directions at a time.
This may create very severe sea-breeze storms.
Tell what causes a sea-breeze storm.
Sea-breeze storm forms over Florida. B
storm
sea breeze
sea breeze
22
Rain Shadows
As moving air hits a mountain, it moves up the side and
over. As the air moves upward, the water vapor cools and
condenses. Rain then falls on the upwind side. By the time
the air reaches the other side of the mountain, it is dry.
So rain does not fall on the downwind side. This causes a
rain shadow. A rain shadow is the area with little rain or
clouds on the downwind side of a mountain.
What causes a
rain shadow?
Rain shadow C
wet side (up)
dry side (down)
Review
Complete the cause and effect statements.
1.During the day, cooler air over water moves
toward land and makes a _______.
2.At night, cooler air over land moves toward
water and makes a _______.
3.When sea breezes push clouds toward the land,
_______ form over the land.
4.When air moves up the side of a mountain, the
water vapor cools and it _______.
23
VOCABULARY
VOCABULARY
air mass
cold front
warm front
barometer
anemometer
How Can
Weather Be
Predicted?
cool air mass
warm air mass
An air mass is a large body of air. All the air in an air
mass has about the same temperature and moisture
level. This map shows warm and cool air masses.
24
A warm front forms where
a warm air mass slides up
and over a cold air mass.
A barometer is a weather
instrument that measures
air pressure.
A cold front forms where a
cold air mass moves under
a warm air mass.
An anemometer is a
weather instrument that
measures wind speed.
25
Reading Focus Skill
cause and effect
A cause is what makes something happen. An
effect is what happens.
Look for the effects of air masses on weather.
Air Masses
An air mass is a large body of air. All the air in an air
mass has about the same temperature and moisture level.
Moisture level is the amount of water in the air.
Temperature and moisture depend on where an air
mass forms. Air masses that form over land are dry. Air
masses that form over water have a lot of moisture.
Air masses that affect North America B
cool air mass
cool air mass
cool air mass
warm air mass
warm air mass
26
warm air mass
warm air mass
Moving air masses cause weather changes. Cold,
wet air can bring snow. Cold, dry air brings cold
weather but little precipitation. Warm, wet air brings
precipitation. Warm, dry air brings warm weather
but little precipitation.
Warm air is lighter than cold air, so air masses
do not mix. When they meet, warm air masses are
pushed upward. Cold air masses sink.
Tell what causes weather changes.
Moving air masses do not mix with each other. B
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Fronts
When air masses meet, a front, or border, forms
between them. A cold front forms where a cold air
mass moves under a warm air mass. The warm air moves
upward. Then it cools and forms clouds. A cold front can
bring rain, thunderstorms, and cooler temperatures.
A warm front forms where warm air slides up and
over cold air. A warm front moves slowly. It often brings
steady rain. Clear, warm weather usually follows.
D Warm front
Cold front C
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A front may not move for many days. This is a
stationary front. Stationary means it does not move. A
stationary front can leave many inches of rain or snow.
Different fronts move differently. This causes different
clouds to form. The types of clouds in an area can help
predict the weather.
What are the effects of a warm front?
D Stratus
clouds can
develop into
rain clouds.
D Cumulus
clouds can
develop into
thunderstorm
clouds.
D Cirrus clouds
mean cool,
fair weather.
29
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Weather maps use symbols and colors to show the
weather. You can guess what the cloud with rain or
the sun means. The key tells what the colors and other
symbols mean.
The National Weather Service makes weather maps.
It uses information from thousands of weather stations.
The stations measure the weather across the country.
Tell how information from weather stations
across the country is used.
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Measuring Weather
Weather instruments measure weather. A thermometer
measures temperature. A barometer measures air
pressure. An anemometer measures wind speed. A
wind vane shows wind direction. A rain gauge measures
precipitation.
How would you know whether the temperature
had fallen?
B Anemometer
B Barometer
Thermometer A
Review
Complete these cause and effect statements.
1. Cold, wet air can bring _______.
2.If a cold air mass moves under a warm air
mass, a _______ forms.
3.Many inches of rain or snow are sometimes
caused by a _______ front.
4.If a warm air mass slides up and over a cold
air mass, a _______ forms.
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GLOSSARY
air mass (air mas) A large body of air that has a similar
temperature and moisture level throughout
anemometer (an•uh•mahm•uh•ter) A weather instrument
that measures wind speed
barometer (buh•rahm•uh•ter) A weather instrument used to
measure air pressure
cold front (kohld fruhnt) The boundary where a cold air mass
moves under a warm air mass
condensation (kahn•duhn•say•shuhn) The process by which
a gas changes into a liquid
evaporation (ee•vap•uh•ray•shuhn) The process by which a
liquid changes into a gas
hail (hayl) Round pieces of ice formed when frozen rain is
coated with water and refreezes
hurricane (her•ih•kayn) A large tropical storm that has winds of
at least 74 miles per hour
land breeze (land breez) A breeze that moves from the land
to the sea
precipitation (pree•sip•uh•tay•shuhn) Water that falls to Earth
rain (rayn) Precipitation that is liquid water
rain shadow (rayn shad•oh) The area with less rain and cloud
cover on the downwind side of a mountain range
sea breeze (see breez) A breeze that moves from the sea to
the land
sleet (sleet) Precipitation caused when rain falls through freezing
air and turns to ice
snow (snoh) Precipitation caused when water vapor turns
directly into ice and forms ice crystals
tornado (tawr•nay•doh) A fast-spinning spiral of wind that
touches the ground
warm front (wawrm fruhnt) The boundary where a warm air
mass moves over a cold air mass
water cycle (wah•ter sy•kuhl) The movement of water from the
surface of Earth into the air and back again
32
Think About the Reading
1. What is the water cycle? How is the water cycle
related to weather?
2. What landforms affect the water cycle? How?
Hands-On Activity
Use a clear empty jar, 2 rubber bands, and a ruler to make a
rain gauge.
1. Stand the ruler against the outside of the jar. Use the
rubber bands to strap the ruler to the side of the jar.
Make sure the bottom of the ruler is lined up with
the bottom of the jar.
2. Place the jar outside where rain can fall into it.
3. After it rains, record the amount. Then empty the jar
and repeat the process each time it rains. How much
rain usually falls?
School-Home Connection
Explain to a family member what you learned about
clouds and why they are different. Together, conduct a
cloud watch for about a week. Record your observations.
Note the date and time, illustrate any cloud formations,
and describe the weather. Review your observations. Do
you see any patterns? Talk about them.