lesson 3 earth’s hydrosphere and atmosphere -...

Every day, freshwater flows from this waterfall. How much freshwater do you use in 1 day?

Earth’s Hydrosphere and Atmosphere

Lesson 3

Seljalandsfoss Waterfall, Iceland

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318ENGAGE

ESS.34 Identify the components of the hydrosphere (ESS-M-A11) ESS.35 Identify the atmosphere as a mixture of gases, water vapor, and particulate matter (ESS-M-A11)

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How much freshwater do you use?

Make a PredictionHow much water do you use in a day for an activity, such as brushing your teeth or washing your hands?

Test Your Prediction

Put the container in the sink.

Turn the water on and pretend to brush your teeth or wash your hands. Run the water as long as you would if you were really doing that activity. Once you are done, turn off the water.

Measure Using the measuring cup, scoop water out of the container into the sink. Keep track of each cup that you pour.

Draw Conclusions

Use Numbers On a chart, figure out how many gallons of freshwater you use for the activity in a week, a month, and a year (16 cups = 1 gallon).

Communicate Discuss with your classmates how much water you used . Exchange data for the amount of water you used for your chosen activity. Whose use of water was closest to their prediction?

Design and complete tables or graphs to display the results of all of the data collected by the other students.

Explore More

Think of a way you can reduce the amount of water that you used. Predict how much water you can save. Redo the activity you chose using your new idea. Were you able to save water? Compare your investigation with a classmate’s. Provide suggestions to improve each others’ ideas.

• container

• sink

• measuring cup

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319EXPLORE

SI.11 Construct, use, and interpret appropriate graphical representations to collect, record, and report data (e.g., tables, charts, circle graphs, bar and line graphs, diagrams, scatter plots, symbols) (SI-M-A4) SI.25 Compare and critique scientific investigations (SI-M-B1)Also covers SI.19

as


The Hydrosphere: Earth’s Water

▶ Essential QuestionHow are Earth’s hydrosphere and atmosphere related?

▶ Vocabularyhydrosphere, p. 320

reservoir, p. 323

aquifer, p. 323

atmosphere, p. 324

air pressure, 324

mantle, p. 326

lithosphere, p. 326

▶ Reading Skill Main Idea and Details

Main Idea Details

▶ Technology e-Glossary and e-Review online at www.macmillanmh.com

ESS.34, ESS.35

Where is water on Earth?Have you ever wondered which parts of Earth

contain water? The hydrosphere (HI•druh•sfeer) is the part of Earth that contains water. Water covers about 75 percent of Earth’s surface. It exists in many forms and in many places in the hydrosphere. Water can be found as a solid in the form of ice or snow; as a liquid in oceans, lakes, and rivers; and in the atmosphere as water vapor or water droplets.

What evidence of water is shown in this photograph of planet Earth?

Clue: List and then look for the different forms of water you know.

Read a Photo

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320EXPLAIN


PACIFICOCEAN

ATLANTICOCEAN

Gulf of Mexico

Mississippi River

G r e a t L a ke s

rr e a tr a t

Earth’s water exists in two basic forms: salt water and freshwater. Most of the water on Earth is salt water, or water that has salts dissolved in it. Ocean water contains salts such as sodium chloride and magnesium chloride. Scientists use the term salinity to describe how much salt is dissolved in water.

Freshwater contains little or no salt. It comes from sources such as rivers and lakes, and also from rainfall. Mostof Earth’s freshwater exists as ice.

Glaciers are large sheets of ice that slowly move. Valley glaciers form at high elevations in areas such as mountains. Continental glaciers cover large parts of the polar regions.

Quick Check

Main Idea and Details Where is

water found in Earth’s hydrosphere?

Critical Thinking Why is water on

Earth’s surface found sometimes as

a solid and sometimes as a liquid?

Parts of Alaska are covered by glaciers.

The Mississippi River is a major source of freshwater.

Ocean water contains many salts.

In winter, water along the shores of some lakes and rivers freezes, forming ice.

Bodies of Wa ter

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321EXPLAIN


What are sources of

freshwater?Many organisms on Earth need

freshwater to survive. About 97 percent of the water on Earth is salt water in the oceans. Roughly 2.3 percent of water on Earth is freshwater that is frozen at or near the North Pole and the South Pole. Another 0.6 percent is liquid freshwater. Finally, 0.1 percent of Earth’s water is present in the air as water vapor. If all the water on Earth

were the size of this page, the amount of freshwater on Earth would be the size of this square.

What causes so much of the water on Earth to be salty? Water that falls as rain or snow is freshwater. As rain runs downhill, it picks up salts from soil and rocks. This water runs into rivers.

Rivers carry these salts into the ocean. Waves pick up salts from rocks and sand. Erupting volcanoes also add salts to the ocean. Each of these sources adds a small amount of salt. Since salts have been added for many millions of years, over time, the amount of salt in the ocean has slowly increased to its current concentration of 3.5 percent.

Freshwater is a limited resource. Most of the freshwater that people use is obtained from running water, standing water, and groundwater.

Running and Standing Water

Many cities and towns were built next to sources of running water, such as streams or rivers. Running water provides a source of freshwater for homes, farms, and businesses.

reservoir

well

streams

snow

aquifer

Usable Sources of Freshwater

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322EXPLAIN


Lakes and reservoirs are bodies of standing water. A reservoir is an artificial lake that is built to store freshwater. Reservoirs are usually made by building a dam across a river. Water is stored behind the dam and released when it is needed.

Groundwater

Groundwater seeps into the ground through aquifers (AK•wuh•fuhrz). An aquifer is an underground layer of rock or soil that has pores and is capable of absorbing water. As the water seeps through, it eventually reaches a layer that does not absorb water. Over the years, freshwater builds up on top of the rock. People pump groundwater out of aquifers through wells so it can be used.

Quick Check

Main Idea and Details What makes

freshwater a limited resource?

Critical Thinking What are some

reasons why one area of an ocean

might be more salty than another?

dam

river

What are ways people use artificial construction to get water?

Clue: Look for artificial construction in the diagram.

Read a Diagram

Earth’s Water

Pour 1 L (1,000 mL ) of water into a beaker. This represents all the water on Earth.

Make a Model Pour 972 mL of this water into a large graduated cylinder and add green food coloring. This represents Earth’s ocean water.

Pour the remaining 28 mL into a medium-sized graduated cylinder. Add blue food coloring. This represents Earth’s freshwater.

Transfer 4 mL of the “freshwater” to a small graduated cylinder. This represents Earth’s groundwater.

Transfer 3 mL of the “freshwater” to another small graduated cylinder. This represents the water in Earth’s lakes and rivers as well as in its soil and air. The remaining freshwater represents Earth’s ice caps and glaciers.

Use Numbers Find the percent of Earth’s water that each graduated cylinder represents. Divide each amount of water (in milliliters) by 1,000. Then multiply each answer by 100.

Use Numbers Make a circle graph of these percentages to show how Earth’s water is distributed.

SI.6, SI.11, SI.15

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323EXPLAIN


Most of the air we breathe in the troposphere is oxygen and nitrogen.

What is in the air?Air surrounds Earth like a

thin blanket. This blanket is the atmosphere (AT•muh•sfeer), the layers of gases that surround Earth. How is the atmosphere important to people and other living things?

Gases

The atmosphere is a mixture of different gases. Most of the atmosphere is made of nitrogen (NI•truh•jun) and oxygen. However, the atmosphere also contains carbon dioxide and other important gases.

Animals and most other organisms need oxygen to live. Plants also need carbon dioxide. The atmosphere allows living things to survive on Earth.

The particles of gas in the atmosphere press on Earth’s surface and everything they surround. The force put on a given area by the weight of the air above it is called air pressure. At sea level, the average air pressure is 1.04 kilograms per square centimeter (1.04 kg/cm2 ), or 14.7 pounds per square inch (14.7 lb/in.2).

The Troposphere

Earth’s atmosphere is made up of layers. The layer closest to Earth’s surface is the troposphere (TROH•puh•sfeer). Compared to the rest of the atmosphere, the troposphere is very thin. Yet all of Earth’s life exists here. In fact the troposphere contains 80 percent of the total amount of air in the atmosphere.

nitrogen 78%

othergases 1%

oxygen 21%

Layers of Earth’s Atmosphere

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324EXPLAIN


thermosphere

mesosphere

stratosphere

troposphere

85 km

50 km

17 km

650+ km

The troposphere is also where all of Earth’s weather takes place. Here the air is always on the move. Air that moves from place to place is called wind. Wind can be as gentle as a light breeze. It can be as fierce as a tornado.Any change in the wind brings a change in the weather.

Other Layers of the Atmosphere

The diagram shows three other layers of Earth’s atmosphere. The stratosphere (STRA•tuh•sfeer) is the layer above the troposphere. The stratosphere has few air particles. Airplanes normally fly within the stratosphere because it is very stable. The stratosphere also contains the ozone layer which absorbs harmful rays from the Sun.

Which layer of the atmosphere is thickest?

Clue: Use subtraction. The numbers tell you the height of each layer above Earth’s surface.

Read a Diagram

Just above the stratosphere is the mesosphere. The air is even lighter in the mesosphere (ME•zuh•sfeer). The coldest temperatures in the atmosphere are found at the top of the mesosphere.

The outermost layer of Earth’s atmosphere is the thermosphere (THUR•muh•sfeer). The thermosphere is where space shuttles orbit. The air is even thinner here as it approaches the near-vacuum of space.

Quick Check

Main Idea and Details How are

the troposphere and the atmosphere

related?

Critical Thinking In what way is

Earth’s atmosphere like an orange

peel? How is it different?

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325EXPLAIN


What is a model of Earth?As you know, the hydrosphere is

the part of Earth that contains water. The atmosphere is the layer of gases that surrounds Earth. What else makes up Earth? Scientists have gathered evidence from earthquakes and volcanoes to form a model of Earth’s interior. The evidence strongly suggests that Earth is made of layers.

Earth’s solid, rocky surface is the crust. The crust includes the continents and the ocean floor. The layer beneath the crust is the mantle. The upper part of the mantle nearest the crust is solid and rigid, or stiff. Together, the crust and the rigid part of the mantle make up what is called the lithosphere (LIH•thuh•sfeer).

The part of the mantle just below the lithosphere is very hot, and scientists think it flows like plastic putty. Beneath the mantle is the core, the central part of Earth. The core is made up of two parts. The outer core is the molten, or fluid, part of the core. The inner core is solid. Earth’s core is extremely dense, and it is under high pressure.

Quick Check

Main Idea and Details Write a brief

summary of the different layers that

make up Earth’s interior.

Critical Thinking What conditions

might make travel to the center of

Earth difficult?

The thin, rigid crust varies from 6 to 70 km in thickness.

The mantle (about 2,900 km thick) is denser near the core.

Lower pressure allows the outer core (about 2,300 km thick) to remain liquid.

Intense pressure makes the inner core a solid ball about 2,400 km in diameter.

Earth’s Layers

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326EXPLAIN


Make a Study GuideMake a three-tab book. Copy the phrases shown. On the inside of each tab, summarize the feature of Earth.

Think, Talk, and Write Vocabulary The crust and the rigid part of Earth’s mantle together make up the .

Main Idea and Details Describe Earth’s hydrosphere and atmosphere.

Main Idea Details

Critical Thinking Given that 75 percent of Earth’s surface is covered with water, why is water considered a scarce resource?

Test Prep Glaciers are part of Earth’s

A atmosphere.B hydrosphere.C mantle.D outer core.

Test Prep In which layer of the atmosphere do we experience weather?

A thermosphereB stratosphereC mesosphereD troposphere

Essential Question How are Earth’s hydrosphere and atmosphere related?

Visual Summary

Earth’s hydrosphere contains freshwater and salt water.

Sources of freshwater include streams, rivers, reservoirs, lakes, and aquifers.

Earth’s atmosphere is made up of different gases.

Expository WritingWrite a report describing the sources

of freshwater in your area. Do research

to find out about local bodies of water.

Which ones contain freshwater? Where

are they located?

Percent of Air Pressure Mt. Everest is the highest mountain on

Earth. The air pressure is 50 percent

less at the peak than at sea level. What

air pressure does a mountain climber

feel at the top of Mt. Everest?

-Review Summaries and quizzes online at www.macmillanmh.com

Writing Link Math Link

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327EVALUATE


Inquiry Skill: CommunicateWhen scientists complete an experiment, they

communicate their results. When you communicate, you share information with others. You may do this by speaking, writing, drawing, singing, or dancing.

▶ Learn ItIn the following activity, you will test whether air can

lift a notebook off the table. Keep notes that include your hypothesis, materials, observations, and conclusion.

Scientists often try new experiments based on work that other scientists have done. If you communicate the details of your experiment, other students can do experiments based on yours. Writing down exactly what you did also lets you plan more experiments with different materials and different variables. If you get an unexpected result or disprove your hypothesis, you should communicate that as well.

▶ Try ItMaterials notebook, 2 balloons, tape, ruler

You know that air has weight and takes up space. Do you think air in a balloon will be able to lift a notebook off a table? If it can, how high will the notebook rise?

Tape two balloons to a notebook so the ends of the balloons stick out. Flip the notebook over so it is on top of the balloons.

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328EXTEND

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▶ Apply ItThink about how you could use air

to lift the book even higher. What would happen if you used bigger balloons? If you placed smaller balloons under each corner of the notebook? How heavy of a book could you lift using these materials?

Plan a new experiment. Test your hypothesis and draw conclusions about using air to lift objects. Then communicate to the class the results of your experiment by writing a report, drawing a cartoon strip, or composing and singing a song!

Blow into one of the balloons. What happens to the notebook? Fill both balloons with as much air as you can.

Using a ruler, measure the height between the table and the notebook.

Communicate Exchange data with other students about the height that air was able to raise your notebook.

Using the data from your classmates, figure out the average height that your class was able to lift the notebooks. Make a chart to compare your results.

Communicate Who was able to raise their notebooks the highest? Was anyone unable to lift it? Discuss any problems that occurred or improvements that could be made to lift the notebook higher.

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329EXTEND

SI.4 Design, predict outcomes, and conduct experiments to answer guiding questions (SI-M-A2) SI.33 Evaluate models, identify problems in design, and make recommendations for improvement (SI-M-B4)Also covers SI.11, SI.19

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lesson 3 earth’s hydrosphere and atmosphere -...

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