Lesson 3
How Do Land Features Affect the Water Cycle?
Fast Fact
Thunderstorms in a Row When cold air over the ocean meets warm air over the land,
squall lines can form. A squall line is a long line of moving thunderstorms. Squall
lines can stretch across the land for hundreds of kilometers! In the Investigate, you
will observe how land and water heat up.
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Investigate
Heating Land and Water
Materials
 2 small plastic or foam cups
 2 thermometers
 dark soil or sand
 stopwatch
 light source with 100-W bulb or greater
 water
Procedure
1. Fill one cup with dark soil or sand. Fill the second cup with water. Place a
thermometer upright in each cup.
2. Time one minute, using the stopwatch. Then measure and record the temperatures of
the two cups.
3. Remove the thermometer after every measurement. Place the cups under the light.
Make sure that both cups get an equal amount of light.
4. After the cups have been under the light for 5 minutes, measure and record their
temperatures. Repeat this step 3 times.
5. Turn the lamp off. Time 5 minutes, and then measure and record the temperatures of
the cups. Repeat this step twice.
Draw Conclusions
1. Describe how the soil and water heated differently. How did they cool differently?
2. Inquiry Skill Scientists use what they observe to form a hypothesis. Use your
observations from this investigation to hypothesize how the weather on Earth
would be different if Earth's surface were mostly land instead of mostly water.
Investigate Further
Does wet soil heat differently from dry soil? Conduct an experiment to find out.
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Reading in Science
VOCABULARY
sea breeze p. 248
land breeze p. 248
rain shadow p. 250
SCIENCE CONCEPTS
 how temperature affects the water cycle
 how landforms affect the water cycle
READING FOCUS SKILL CAUSE AND EFFECT Look for ways that landforms
affect the water cycle.
Sea Breezes and Land Breezes
Have you ever been to the beach on a hot day? It might be so hot that your feet burn
when you walk on the sand. But when you go into the water, you quickly cool off.
That's because the water is cooler than the sand.
Land heats up much more quickly than water. Land also cools down more quickly than
water. Because of this, the temperature of the air over land is almost always
different from the temperature of air over nearby water. During the day, the air over
water is cooler than the air over land. The hot air over a beach is pushed upward by
the cool air moving in from over the water. This causes a sea breeze. A sea breeze
is a breeze moving from the water to the land. During the night, the land becomes
cooler than the water. This causes a land breeze. A land breeze is a breeze moving
from the land to the water.
CAUSE AND EFFECT What causes a land breeze?
---see pictures
Warm air is pushed upward as cool air moves into its place. During the day, the
air over land is warmer than the air over water, which causes a sea breeze.
During the evening, the air over water is warmer than the air over land, which
causes a land breeze.
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---see pictures
Over the Florida peninsula, sea breezes can blow from different directions.
Doppler radar can be used to track sea breeze storms.
Sea Breeze Storms
You learned in Lesson 1 that when water vapor cools, it condenses to form
precipitation. Sometimes, cool sea breezes push clouds toward the shore. The
clouds can then produce storms over the land. These storms are called sea breeze
storms.
A peninsula is a piece of land that is surrounded by water on three sides. Over a
peninsula like Florida, sea breezes can come in from the east and from the west.
The collision of the two sea breezes causes the air to become unstable. If the two
bodies of air have a lot of water vapor, a very strong sea breeze storm could form
over the center of the peninsula. This type of sea breeze storm happens often in
Florida during the summer.
CAUSE AND EFFECT What causes a sea breeze storm?
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---see picture
WET SIDE
As air is pushed upward, it cools and releases its moisture.
DRY SIDE
As the cool air moves downward, it warms and dries out as it spreads over land.
Rain Shadows
Shorelines are not the only landform that affects the water cycle. Mountains do, too.
Suppose a moving body of air hits the side of a mountain range. What happens?
The air can't move through the mountains. Instead, the air is pushed up the side of
the mountains and then over them. As the air moves up, it cools. The water vapor in
the cooler air condenses and brings rain to that side of the mountains. By the time
the air reaches the other side, the air is dry. So, it doesn't rain on the other side. This
causes a rain shadow. A rain shadow is the area on the far side of a mountain
range that gets little or no rain or cloud cover.
CAUSE AND EFFECT What is the effect of a rain shadow?
Insta-Lab
Lightning and Thunder
The next time a thunderstorm is in your area, watch for lightning. When you see the
lightning, start counting, "One-Mississippi, two-Mississippi, ..." and so on. When
you hear the thunder, stop counting. For every three seconds you count, the
thunderstorm is about one kilometer from you. How far away is the thunderstorm?
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1. CAUSE AND EFFECT Copy and complete these graphic organizers.
---see chart
2. SUMMARIZE Write a paragraph summarizing the lesson. Start with this sentence:
The water cycle is affected by landforms.
3. DRAW CONCLUSIONS Will sea breeze storms happen more often in warm places
or cool places? Explain.
4. VOCABULARY Explain the difference between a land breeze and a sea breeze.
Test Prep
5. Critical Thinking Explain why a mountain may be green on one side and desertlike
on the other.
6. How does warm air move?
A. It falls.
.
B. It is pushed upward .
C. It spins
D. It stays still.
Writing
Expository Writing
Suppose that you are an early explorer of a mountain range that experiences the rain
shadow effect. Write a journal describing your explorations of the range.
Math
Solve Problems
A sea breeze storm is moving across Florida from the northeast to the southwest at 23
km/hr. How long does the storm take to reach Tampa if it started above Orlando,
which is 117 km away?
Physical Education
Water Sports
Many water sports, such as sailing, make use of sea breezes. Choose a sport that uses
sea breezes, and write a simple how-to guide for this sport.
For more links and activities, go to www.hspscience.com
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