Download Earth`s Hydrosphere and Atmosphere Lesson 3

Lesson 3
Earth’s
Hydrosphere and
Atmosphere
Seljalandsfoss Waterfall, Iceland
Every day, freshwater flows from this
waterfall. How much freshwater do you
use in 1 day?
318
ENGAGE
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)
How much freshwater do you use?
Materials
Make a Prediction
How 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.
• container
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.
• sink
• measuring cup
Step
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.
Step
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.
SI.11 Construct, use, and interpret appropriate graphical representations to collect, record,
a report data (e.g., tables, charts, circle graphs, bar and line graphs, diagrams, scatter plots,
and
s
symbols)
(SI-M-A4) SI.25 Compare and critique scientific investigations (SI-M-B1)
Also covers SI.19
319
EXPLORE
Where is water on Earth?
▶ Essential Question
How are Earth’s
hydrosphere and
atmosphere related?
ESS.34, ESS.35
▶ Vocabulary
hydrosphere, p. 320
reservoir, p. 323
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.
aquifer, p. 323
atmosphere, p. 324
The Hydrosphere: Earth’s Water
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
Read a Photo
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.
320
EXPLAIN
Bodies of Wa ter
In winter, water along the
shores of some lakes and
rivers freezes, forming ice.
Great
Lak
es
Mis
sissi
Parts of Alaska are
covered by glaciers.
ppi R
i ve r
PACIFIC
OCEAN
ATLANTIC
OCEAN
Ocean water contains
many salts.
Gulf of Mexico
The Mississippi River
is a major source of
freshwater.
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. Most
of 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?
321
EXPLAIN
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.
snow
Usable Sources of Freshwater
streams
reservoir
well
aquifer
322
EXPLAIN
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?
Earth’s Water SI.6, SI.11, SI.15
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.
Read a Diagram
dam
What are ways people use artificial
construction to get water?
river
Clue: Look for artificial construction in
the diagram.
323
EXPLAIN
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).
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 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.
Layers of Earth’s Atmosphere
oxygen 21%
other
gases 1%
nitrogen 78%
Most of the air we breathe in the
troposphere is oxygen and nitrogen.
324
EXPLAIN
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.
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?
650+ km
thermosphere
85 km
mesosphere
50 km
Read a Diagram
stratosphere
Which layer of the atmosphere is thickest?
17 km
Clue: Use subtraction. The numbers tell you the
height of each layer above Earth’s surface.
troposphere
325
EXPLAIN
Earth’s Layers
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.
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).
326
EXPLAIN
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?
Visual Summary
Earth’s hydrosphere
contains freshwater and
salt water.
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.
Sources of freshwater
include streams, rivers,
reservoirs, lakes, and
aquifers.
Main Idea
Details
Critical Thinking Given that 75 percent
Earth’s atmosphere is
made up of different
gases.
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.
Make a
Study Guide
Make a three-tab book.
Copy the phrases shown.
On the inside of each
tab, summarize the
feature of Earth.
Test Prep In which layer of the
atmosphere do we experience weather?
A thermosphere
B stratosphere
C mesosphere
D troposphere
Essential Question How are Earth’s
hydrosphere and atmosphere related?
Writing Link
Math Link
Expository Writing
Percent of Air Pressure
Write 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?
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
327
EVALUATE
Inquiry Skill: Communicate
When 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 It
In 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 It
Materials 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.
328
EXTEND
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.
▶ Apply It
Think 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!
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
329
EXTEND