Download You Will Discover

You Will Discover

How ocean water and fresh water are different

How the water cycle gives us fresh water.

What causes weather.
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How we predict weather.
Chapter 6
Water Cycle and Weather
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Build Background
How does Earth’s water affect weather?
Evaporation
Condensation
Precipitation
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Chapter 6
Vocabulary
Evaporation page 186
Condensation page 187
Precipitation page 187
humidity page 190
front page 191
meteorologist page 194
barometer page 194
anemometer page 195
wind vane page 195
Meteorologist Scientists called meteorologists study weather conditions.
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Lab Zone
Directed Inquiry
Explore How can you make fresh water from salt water?
Some countries without enough fresh water make fresh water from salt water.
Materials
salt water and spoon
small cup and bowl
plastic wrap and tape
marble
Process Skills
You can write, speak, or draw pictures to communicate information.
What to Do
1. Pour 5 spoonfuls of salt water into a bowl. Set a small cup in the middle of the bowl.
Cover the bowl with plastic wrap.”
Tape the plastic wrap to the bowl The plastic wrap should not touch the small cup.
Place a marble above the small cup.
2. Place in sunlight for several hours.
3. Remove the marble, plastic wrap, and cup. Put the bowl and cup in a warm place. Let
the water evaporate for about 3 days.
4. Observe the bottom of each container.
Explain Your Results
1. Communicate What did you find in the bottom of each container? Explain.
2. Predict Think about the variables that affect evaporation. How could you speed up
evaporation? Describe how you could test your prediction.
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How to Read Science
Reading Skills
Cause and Effect
Linking causes and effects can help you better understand what you read. Writers
sometimes communicate cause and effect with words such as because, since, so,
and as a result.
• A cause may have more than one effect. An effect may have more than one cause.
Sometimes an effect leads to another event, which creates a chain of causes and
effects. Some of the causes and effects in the article are marked.
• You can use a graphic organizer to show cause and effect.
Newspaper Article
Skating on Thin Ice
A skater was rescued from icy waters in Lily Pond today. Last night temperatures
dropped, causing the ice on the pond to thicken. In the chilly dawn, the skater glided
over the ice. But the temperature rose, so the ice began to melt. As a result, the ice
was much thinner at noon when the skater returned. Since the thin ice could not
support his weight, the skater fell through the ice and into the water near the edge of
the pond. He recovered quickly, because he was rescued right away.
Apply It!
Make a graphic organizer like the one shown to communicate the causes and effects in
the newspaper article. If an event is BOTH a cause and an effect, you should write it
in each box.
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You Are There!
You are gazing at Earth from space. The giant blue ball turns slowly. Huge chunks of
brown and green with splashes of white creep into view, cross the blue ball, and
disappear behind it. The chunks are Earth's continents and islands. The vast expanse
of blue is the world's great ocean. Masses of white clouds drift across the lands and
ocean. How does Earth's water affect why clouds form and how they move?
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Lesson 1
Where is Earth's water?
Any ocean that you might step into is linked to all the oceans in the world. The world's
oceans connect to form one huge mass of salty water, with large and small areas of
land.
Earth—The Water Planet
Throughout history, people have used bodies of water to travel from place to place.
Because almost 4 of Earth's surface is covered with water, they had very little
choice. Water provides a home and food for millions of Earth's organisms. In turn,
these organisms are food for people.
Earth's water is always in one of three states. At a temperature of 0°C, water freezes into
a solid called ice, and ice melts into water. At a temperature of 100°C, water
becomes an invisible gas called water vapor.
Some of the water near Earth's surface is water vapor in the atmosphere. But more than
97/100 of Earth's water is in the oceans and the seas. The seas are smaller areas of
the ocean. Most of the rest of Earth's water is frozen in glaciers and polar ice caps.
Less than 1/100 is in rivers and lakes.
People have named sections of Earth's great ocean. The table shows the names and areas
of some of the sections.
1. Checkpoint About how much of Earth's water is frozen in glaciers and ice caps?
2. Math in Science Look at the table above. About how much greater is the area of the
Pacific Ocean than the area of the Atlantic Ocean?
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Salty Water
"Water, water, everywhere, Nor any drop to drink." These lines in a famous poem
describe a crew on an ocean ship that has run out of drinking water. Water is all
around them. How could they run out of drinking water?
If you have ever tasted ocean water, you know the answer. It tastes very salty. But taste
is not the main problem. Ocean water is not healthy for drinking. Your body cannot
use water that is as salty as ocean water.
But why is the ocean salty? Water is a liquid made up of hydrogen and oxygen. Ocean
water is a mixture of water and many dissolved solids. Most of the salt in ocean
water comes from rocks and soils on the land. Rivers carry dissolved salts and
minerals to the ocean. The most common salt in the ocean is sodium chloride, the
same salt that's in your saltshaker. The ocean supplies much of our table salt and
some of our minerals.
Lakes and rivers make up a part of Earth’s fresh water.
Most of Earth’s fresh water is frozen in polar ice caps and glaciers.
Oceans and seas are filled with salty water. They cover most of Earth.
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Differences in Saltiness
Saltiness of the water near the ocean's surface varies from place to place. In warm, dry
places, ocean water turns rapidly into water vapor in the air. The salt that's left
behind makes the water even saltier. Some of the saltiest water on Earth is located
in the Red Sea, which has deserts on three sides.
Ocean water is less salty near the North and iouth Poles. Less salt can dissolve in the
cold water :here. And water turns to vapor more slowly in lower temperatures. The
ocean is also less salty in areas where rivers, melting ice, or heavy rains add plenty
Af fresh water. For example, many rivers flow into the 3altic Sea. Its water is less
salty than most ocean water.
Most of Earth's water is salty ocean water. Most of Earth's fresh water is frozen in
glaciers and ice caps. People cannot use it for drinking. They cannot use it to keep
land plants and animals alive. Earth's liquid Fresh water is underground or in lakes,
rivers, and streams. The water vapor in the air and the liquid and Frozen water that
fall through the atmosphere are all Fresh water.
Lesson Checkpoint:
1. Why is the water in the Baltic Sea less salty than most ocean water?
2. Is the water in the Red Sea more or less salty than average? Explain your answer.
3. Cause and Effect Why is ocean water more salty than average in warm and dry
places?
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Lesson 2
How do water and air affect weather?
Why do some places get lots of rain while other areas get very little? The way water
moves in and out of the atmosphere affects our lives.
How Water Is Recycled
Earth's water is always being recycled. The never-ending movement of water from
Earth's surface to its atmosphere and back again is called the water cycle. You can
see an example of the water cycle as puddles disappear after a rain. Some water runs
into drains that flow into lakes, rivers, or the ocean. The rest is in the air. Water is
made of small particles that are constantly moving. As the Sun's energy warms the
water, the particles move faster. They fly away from the liquid water and change
into a gas called water vapor.
The process of changing liquid water to water vapor is called evaporation. The higher
the temperature, the faster water changes from liquid to gas.
Evaporation
Water is stored in lakes, oceans, glaciers, marshes, soil, and spaces in rock. It evaporates
in the Sun's warmth. Some water vapor also comes from the leaves of plants.
Condensation
When moist air rises, it cools. The water vapor in it condenses in the atmosphere. These
tiny droplets of liquid water form clouds and fog.
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To understand the next step in the water cycle, think of what happens when you breathe
on a cold window. The cold glass cools the water vapor in your warm breath. The
water vapor turns into a liquid that fogs up the window. The process of water vapor
becoming liquid water when it cools is called condensation.
Like the fog from your breath, a cloud is made of tiny drops of water or ice crystals. The
drops and crystals combine with others until they become so large and heavy that
gravity pulls them downward. Then they fall as precipitation, which is any form of
water that falls to Earth. The cycle begins again.
The Sun's energy powers the water cycle that provides fresh water from the ocean.
Temperature, air movement, and how much water vapor is in the air affect how
quickly water evaporates and condenses. Because land features affect temperature,
they affect the water cycle too. When wind blows moist air up one side of a
mountain, clouds form there. More precipitation falls than on the other side of the
mountain.
1 .Checkpoint What is the water cycle?
2. Technology in Science Old desalinators used evaporation and condensation to
remove salt from ocean water. Use the Internet to find out how modern desalinators
work.
Precipitation
Depending on air temperatures and wind conditions, the water may fall as rain, snow, or
hail. If the air temperature in or below the cloud is above freezing, th water vapor
will condense and fall as rain. If the air temperature is below fr~ezing, water falls as
snow, sleet, or hail. Most precipitation falls on oceans.
Storage
The water from precipitation over land sinks into soil and underground pores in rock.
Some water runs off the land or seeps from the ground into streams, rivers, and
lakes. Most of it falls, flows, or seeps into the ocean.
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Earth's Atmosphere
When you look up on a clear day, you seem to see a high, blue ceiling. You are really
looking through 9,600 km (about 6,000 mi) of air. The blanket of air that surrounds
Earth is its atmosphere. Like other matter, air has mass and takes up space.
Air is made up of a mixture of invisible gases. Almost 4/5 of Earth's atmosphere is
nitrogen. Most of the rest is oxygen, but small amounts of carbon dioxide gas are
also present. The part of the atmosphere closest to Earth's surface contains water
vapor. The amount of water vapor depends on time and place. For example, air over
an ocean or a forest has more water vapor than air over a desert.
Gravity pulls the mass of air toward Earth's surface. The pushing force of air is called air
pressure. Air pushes with equal force in all directions. At any moment, many
kilograms of gas press down on your school building. They do not crush it because
the air inside the building exerts pressure too. Air pushing down is balanced by air
pushing up and sideways. Air pressure decreases as you go higher in the
atmosphere.
Air Pressure
Air pressure also changes with temperature. As the air near Earth's surface warms, its
particles move farther apart. The air pushes down with less pressure, and then it
rises. An area of low pressure forms. If the air near Earth's surface cools, the
particles in the air become more closely packed. This denser, cooler air sinks. An
area of high pressure forms.
Air moves from a place with high pressure to a place with low pressure. The moving air
is called wind. The name of a wind is the direction from which it comes. A north
wind comes from the north and moves toward the south. Winds near the ocean are
sometimes named differently, as you can see in the diagrams.
Land Breeze
A land breeze blows from the land toward the sea. At night, the water is warmer than the
land. The air above the land is cooler, so it sinks. This creates high pressure at the
surface of the land. The air above the land moves toward the water.
Sea Breeze
A sea breeze blows from the sea toward the land. During the day, the air above the land
is warmer than air above the water. The air rises, creating low pressure at the
surface of the land. The air above the water moves toward the land.
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As you go even higher, air pressure keeps decreasing.
Higher in the atmosphere the particles in the air can move farther apart. Air pressure is
lower.
The air particles higher in the atmosphere squeeze the air particles at Earth's surface
close together. Dense, closely packed particles exert greater pressure than loosely
packed particles.
Lesson Checkpoint
1. What happens when water vapor cools?
2. What happens to air pressure as you go higher in the atmosphere?
3. Cause and Effect How do differences in air pressure cause wind?
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Lesson 3
What are air mass?
Air masses affect weather all the world. As they move, so does the type of weather they
carry.
Air Masses
An air mass is a huge body of air that has nearly the same temperature and humidity.
Humidity is the amount of water vapor in the air. The way air masses move and
interact causes most weather. Air masses form over large areas of land or water. For
several days or weeks, an air mass is heated or cooled by the area over which it
forms. An air mass that forms in the polar areas will be cool or cold. An air mass
that forms in a tropical area will be warm or hot.
An air mass has water vapor that evaporates from the land or water below it. So, air
masses that form over water have greater humidity than those that form over land.
An air mass that forms over a tropical ocean will probably be both warm and humid.
If the air mass forms over a cool ocean, it will be cool and moist.
As an air mass moves, it takes its temperature and humidity to another place. Scientists
predict weather by tracking where an air mass is moving, what other air masses it
will meet, and how it will meet them. Weather is the result of how air, water, and
temperature interact.
Cold air slides under the warm air and forces the warm air up.
Air masses from the south bring warmer weather than those from the north. Moist
air forms over the ocean. Dry air forms over land.
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Air in the warm air mass cools and the water vapor in it condenses into clouds.
Rapidly rising air causes clouds to build upward.
When Air Masses Meet: Cold Front
Global winds over North America usually blow air masses from west to east. As an air
mass moves, it collides with air masses with different temperature and humidity.
The different air masses do not mix. The area where the two air masses meet is
called a front. Two types of fronts are cold fronts and warm fronts.
A cold front forms when a cold air mass bumps into a warm air mass that is moving
more slowly or not moving at all. The density of cold air is greater than the density
of warm air. The denser cold air sinks under the warm air. The warm air along the
front cools as it is pushed upward. Water vapor in the cooling air condenses into
clouds. You can usually see a line of clouds along a cold front.
Cold fronts often cause strong winds and brief, heavy precipitation. In fact,
thunderstorms may develop along the front. But cold fronts usually move faster than
warm fronts, so the precipitation and other weather conditions they bring do not
usually last long. The front often passes quickly, the skies clear, and the colder air
mass replaces the warmer one. The weather turns fair and cooler.
1. Checkpoint Why does an air mass that forms over a desert have low humidity?
2. Art in Science Draw an outdoor place you like as it would look. when a cold front
passes. Be sure to include the sky and the clouds
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When Air Masses Meet: Warm Front
When a warm air mass runs into a cold air mass that is moving more slowly, a warm
front develops. The warm air is lighter and has less pressure than the cold air mass.
The warm air moves forward and creeps over the trailing edge of the cold air mass.
As the warm air rises, it cools. The water vapor in it condenses into clouds.
Warm fronts usually move more slowly than cold fronts do. The air is lifted more slowly
and spreads out more so it affects weather over a larger area. Warm fronts usually
bring steady, long-lasting precipitation. Air temperatures are usually higher after a
warm front passes.
The warm air mass cools as it rises. The water vapor becomes ice crystals. The high
cirrus clouds that form are signs of the advancing warm front.
Thick stratus clouds form close to the ground and may begin to drop rain or snow.
Later, when the sky clears, fluffy cumulus clouds may appear.
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Clouds
Cloud formation begins as the Sun's energy warms water in oceans, lakes, rivers, and the
ground. The heated water evaporates. The Sun's energy warms the air holding the
water vapor. The air rises and cools. The water vapor becomes the tiny water
droplets and ice crystals that make up clouds.
Clouds with many shapes, sizes, and colors move across the sky. Conditions in the
atmosphere determine what a cloud is like. Since 1803, scientists have classified
types of clouds. Today, the ten names given to the major types of clouds are
combinations of three basic types: cumulus, stratus, and cirrus. Scientists add alto to
the name if the clouds are very high or nimbo if they are rain-bearing.
Cumulus clouds are thick, white, and puffy, like piles of cotton. They sometimes appear
in fair or good weather and may reach very high in the sky. Stratus clouds are flat
layers of clouds that form close to Earth's surface. Cirrus clouds are feathery clouds
that form high in the atmosphere when water vapor turns to tiny crystals of ice.
They are sometimes called "mares' tails."
Lesson Checkpoint
1. What is an air mass?
2. Weather is caused by variations in what three basic ingredients?
3. Cause and Effect How does the Sun cause clouds to form?
Cirrus
Altostratus
Cumulus
Cumulonimbus
Stratus
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Lesson 4
How do we measure and predict weather?
Weather is the day-to-day changes in temperature, winds, precipitation, and other
conditions in the atmosphere. Climate is the usual year-after-year weather in an
area.
Measuring Weather
Temperature, air pressure, and water are three basic weather factors that affect weather
conditions. The ocean also affects weather and climate around the world. Ocean
currents move warm water to cold lands and cold water to warm lands. So,
temperatures of land areas near coasts might be milder than those farther from the
ocean. Water heats and cools more slowly than land does. The land and sea breezes
that result affect temperature on land.
Scientists called meteorologists study weather conditions. They also look at temperature,
water, and air movement. Today, almost all of the measurement data that
meteorologists use are collected automatically at weather observation stations.
You probably know that a thermometer measures air temperature. Air pressure is
measured with a tool called a barometer. Air pressure can be measured in units
called millibars (mb). For example, a reading of 1000 mb means higher air pressure
than a reading of 900 mb. The first tool to measure air pressure was the mercury
barometer, invented in 1643 by Evangelista Torricelli. Today, air pressure is also
measured with an aneroid barometer.
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Air Pressure and Weather Conditions
Even without a measuring tool, you can tell something about air pressure by looking
outside. When air pressure is low, the weather is often damp and cloudy. When air
pressure is high, the weather is usually dry and clear. So on a sunny day with a
bright blue sky, you know the air pressure is probably high.
Wind also affects weather. Wind speed is measured with a tool called an anemometer.
Most anemometers have three or four cups that are shaped like halves of small,
hollow balls. The faster the cups spin in the wind, the higher the wind speed shown
on the anemometer. A wind vane shows the direction from which the wind is
blowing. The pointer on the wind vane points into the wind. You may have seen
wind vanes on rooftops.
Meteorologists use a rain gauge to measure the amount of rainfall. The top of the rain
gauge collects rain and directs it into a small tube with numbered markings. The
numbers show in inches or centimeters how much rain has fallen. Meteorologists
measure the humidity with a tool called a hygrometer.
The difference between the temperature sensed by a dry bulb and one covered with
a wet cloth can be used to calculate humidity.
1. Checkpoint What does a barometer measure?
2. Social Studies in Science In a newspaper or on the Internet, look up daily high and
low temperatures for Boston, Oklahoma City, Miami, Santa Fe, San Francisco, and
a city near you. Which cities have the greatest difference between the high and the
low? How do you explain the difference?
Anemometer
Hygrometer
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Predicting Weather
You usually know what weather will be like in each season. For example, you know
most summer days will be warmer than most winter days. Predicting day-to-day
changes is more of a challenge.
A weather forecast is a prediction of what the weather will be like for the next few days.
Meteorologists measure temperature, precipitation, air pressure, and wind over a
large area. They use the measurements to find high and low pressure areas and
fronts. They use data from current weather conditions to make the forecast.
To forecast weather for tomorrow, most meteorologists compare computer models.
Weather radar is one source of data for the models. With radar pictures, forecasters
can see how the atmosphere is changing. Weather radar can track precipitation.
Meteorologists can see where rain is falling. They can predict where and when it is
likely to fall next.
Tracking Weather
Meteorologists use charts and maps to record measurements and information from
weather satellites and radar. Then they analyze the data and use computer models to
predict the weather.
Charts are used to record daily weather conditions. For example, this chart shows high
and low temperatures and precipitation.
Newspapers often have weather information for larger cities.
A weather map shows fronts and how they are moving. A stationary front is
standing still.
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Reading Weather Maps
A weather map uses symbols to show fronts and weather conditions in different places.
A key on the map explains the symbols. Curving lines connect locations with the
same air pressure. The letters H and L are used to show high and low pressure
systems. Triangles and half circles stand for cold and warm fronts. Some maps
show more weather information as well.
1. Checkpoint How are curving lines used on a weather map?
2. Math in Science On the Internet or in a newspaper, look up the daily high and low
temperatures in your area for five days in a row. Use the data to make a line graph.
Use one color for the highs and another color for the lows.
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How Weather and Climate Have Changed
About four billion years ago, Earth cooled. Its atmosphere formed. Since then, Earth's
climate has had dramatic changes from very cold periods to warm periods. During
the last cold period, thick ice sheets stretched from the poles to cover almost one
third of Earth.
Scientists have different ways of learning about Earth's past climate. They drill into ice
from glaciers to find what the climate was like when the ice formed. For example,
tiny bubbles of air frozen during the last cold period show that the atmosphere
contained less carbon dioxide than it does today. Cores of ice can provide evidence
of rapid temperature changes in the area.
Another way scientists get information about the climate in a given place and a certain
year is from tree rings. Each ring in a cut tree trunk shows one year's growth. The
wider the ring, the better the growing conditions for the tree.
Scientists can also examine Earth's crust. They use fossils and chemical analyses to
estimate when each layer of crust formed. They can also use fossils to estimate the
climate at the time the layer was formed. For example, characteristics of fossil
leaves of trees tell about the climate when the trees lived.
At Present
For at least the last two and a half million years, Earth has had climatic cycles. A warm
period is followed by a cold period and then another warm period and so on. Today,
we are in a warm period. The last cold period ended about 10,000 years ago. Earth's
temperature and climate change slowly during these cycles. Even so, many
scientists are concerned that people are causing some changes in Earth's temperature
to happen too quickly.
A wide ring shows that the weather was favorable, and the tree grew well.
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In the Future
When people burn fossil fuels, they add carbon dioxide and other pollutants to the
atmosphere. Water vapor and carbon dioxide are common "greenhouse gases" in
our atmosphere. In the right amounts, greenhouse gases help keep Earth warm. But
extra greenhouse gas can cause Earth's temperature to increase. If Earth becomes
just a few degrees warmer, climates may change. For example, the southern polar
ice cap could melt, putting more water into the oceans. Higher ocean levels might
cause flooding in low areas near coasts.
Government leaders and scientists all over the world are looking for ways to replace
fossil fuels with cleaner energy forms. They are looking for ways to help people use
less energy to power their activities.
Lesson Checkpoint
1. Where can water be found on Earth?
2. Describe the formation and type of clouds along a warm front.
3. Writing in Science Persuasive Suppose you are mayor of your town or city. Write a
notice for a public meeting. Explain how burning fossil fuels can affect the global
climate. Ask people to come to the meeting and discuss ways to reduce the use of
fossil fuels in your town or city.
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Lab Zone
Guided Inquiry
Investigate How does water change state?
Materials
cup and thermometer
metric ruler
water
computer or graphing calculator (optional)
What to Do
1. Fill a cup with water to a height of about 30 mm. Accurately record the height and
temperature of the water.
Your teacher will put your cup in a freezer.
2. Freeze the water overnight. Then record the height and temperature.
3. When the ice just begins to melt, record the height and temperature.
4. When all the ice has melted, record the height and temperature.
Process Skills
You interpret data when you use data to answer questions.
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5. Leave the cup at room temperature. Record the height and temperature for 3 more
days.
6. Make a bar graph showing how the height you measured changed.
Explain Your Results
1. How did the height of the water change? Explain.
2. Interpret Data As the temperature changed, what changes of state occurred? Was
thermal energy added or removed during each change?
3. Based on your graph, predict how long it will take for the water to evaporate
completely.
Go Further
What would happen if you added salt to the water before freezing? Make a plan to find
out.
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Math in Science
Graphing Temperatures
In the area where you live, how much does the temperature change within a few
hours or within a day?
A line graph shows how data change over time. The line graph below for August 21,
2003, shows how the temperature in one city changed during an 1 8-hour period on
that date.
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Use the line graph on page 202 to answer the questions.
1. What was the highest temperature in this city on August 21, 2003? How do you
know?
2. On the line graph, the line between 12:00 Noon and 2:00 P.M. does not go up or
down. What does this tell you?
3. Does the line graph tell you what was the lowest temperature in this city for August
21, 2003? Explain.
4. For the same city, the record high temperature on August 21 is 87°F. The normal high
temperature for that date is 76°F. Make a bar graph comparing the highest
temperature on August 21, 2003, with the record high and the normal high.
Lab Zone
Take-Home Activity
Find a weather report in your daily newspaper, on the Internet, or on television or radio.
Make a bar graph comparing yesterday's highest temperature with yesterday's
lowest temperature.
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Chapter 6 Review and Test Prep
Use Vocabulary
anemometer (p. 195)
Humidity (p. 190)
Barometer (p. 194)
Meteorologist (p. 194)
condensation (p. 187)
Precipitation (p. 187)
Evaporation (p. 186)
wind vane (p. 195)
front (p. 191)
Use the term from the list above that best completes the sentence. Use a term only once.
You will not use every term.
1. A(n)
is the area where one air mass meets another.
2. A(n)
points in the direction from which the wind is blowing.
3. A weather forecast is a prediction made by a scientist called a(n)
4.
.
is the amount of water vapor in the air.
5. A (n)
measures are pressure.
6. A (n)
measures wind speed.
7. Water vapor changes to liquid water in a process called
.
Explain Concepts
8. Use as many vocabulary terms as possible to explain the role the Sun plays in the
water cycle.
9. What type of front is approaching if you see cirrus clouds high in the sky? Explain
how you know.
10. Why do clouds almost always cover the tops of some mountains?
Process Skills
11. Interpret Data Which month had no rainy days?
12. Infer What tool was used to gather the data on the chart?
13. Communicate You are taking a balloon ride high in the atmosphere. Describe how
the air changes as the balloon rises higher in the atmosphere.
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Cause and Effect
14. Make a graphic organizer like the one shown below. Complete it to show how a cold
front forms.
Test Prep
Choose the letter that best completes the statement or answers the question.
15. Which is an example of precipitation?
a. evaporation
b. condensation
c. snow
d. clouds
16. Which does NOT affect how quickly water evaporates or condenses?
F. air movement
G. humidity
H. temperature
I. wind direction
17. Most of Earth's water is
a. in the oceans.
b. underground.
c. frozen in glaciers.
d. in clouds.
18. To predict the weather in your area tomorrow, you would need all of the following
tools except
F. a barometer.
G. a rain gauge.
H. an anemometer.
I. a thermometer.
19. Explain why the answer you chose for Question 18 is best. For each answer you did
not select, give a reason why it is not the best choice.
20. Writing in Science Expository Write a weather prediction for a TV news show.
Use a weather map from a newspaper to get information for your report.
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Eye in the Sky
Observing Weather From Space
Where do scientists find the information they need to understand and predict weather?
NASA provides much of the information. NASA uses special tools, instruments,
and spacecraft to gather information about the atmosphere, ocean currents, polar ice
caps, and the global water cycle. Scientists use the data to learn about how the air,
water, and temperature changes interact.
In one of NASA's programs, scientists use satellites and other special tools to study
Earth as one whole environmental system. The program provides information that
seeks to give more accurate weather predictions. This information may help
fishermen and people who manage farms and forests. It will likely also provide
clues about how climate will change.
NASA has nearly 20 satellites in orbit studying Earth systems. One is named Terra. The
name Terra means "Earth." This name was the winner of NASA's "name the
satellite" contest for students. Terra's instruments collect information about each
point in the atmosphere or on Earth's surface.
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Terra has a twin satellite named Aqua. The word Aqua means "water." Aqua and Terra
circle Earth on different schedules. These satellites and others help scientists
observe the land, ocean, and atmosphere all over the world throughout every day.
They help scientists learn how Earth's climate system changes.
The instruments on the satellites use light, heat, microwaves, and other types of energy
to gather data. They measure the height and motion of clouds. They also provide
data about water evaporation and the movements of water vapor throughout the
atmosphere. They observe storms, wind patterns, and other parts of weather.
Scientists use this information to answer questions about weather and climate. They
put the information into computer models that describe or help predict climate and
weather.
Lab Zone
Take-Home Activity
In library books or on the Internet, find some photographs of Earth taken from space.
What can you tell about weather or atmospheric conditions from the photographs?
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Biography
Joanne Simpson
Dr. Simpson tested some of her ideas by flying through clouds and even hurricanes.
Knowing what kind of weather to expect is very important to us. We want to know what
the weather will be like when we travel or plan activities. Weather reports warn us
of storms, too. Dr. Joanne Simpson is the chief scientist for meteorology at NASA's
Goddard Space Flight Center. Her research on weather helps warn us of severe
storms.
Joanne Simpson began studying clouds when she was a 1 6-year-old student pilot. In
1949, she became the first woman to receive a doctoral degree in meteorology. She
studied models of cloud systems, cyclones, and the way the ocean and the
atmosphere affect each other.
Before joining NASA in 1979, she was a university professor. She also worked at the
National Oceanic and Atmospheric Administration (NOAA) in Washington, D.C.
One of her first projects at NASA was studying severe storms. She was the project
scientist for the Tropical Rainfall Measuring Mission Observatory before she
became the chief scientist for Meteorology.
Dr. Simpson has received many honors for her work in meteorology. Recently she was
given the Charles F. Anderson Award by the American Meteorological Society. She
has helped many young scientists be successful in their careers.
Lab Zone
Take-Home Activity
Suppose you met Dr. Simpson. Write three questions that you would ask her about
predicting the weather or about becoming a meteorologist.
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