What do you already know about clouds?
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Congratulations! You have completed this section. |
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Big puffy white clouds, dark gray rain clouds. When you look up into the sky you could see many different types of clouds. They are not only pretty, they are also an important part of nature. In this unit, you will explore clouds, what they are made of, and their role in the water cycle. |
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Have you ever lain on the beach or field and watched a huge
cloud float by? Were you amazed at how slowly it was changing?
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Sometimes it is in a liquid form: Water flows in a river, an
ocean, and in your sink.
Draw a picture of yourself doing something with liquid water. For example, swimming, drinking, walking in the rain. Take a snapshot of your drawing. |
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Why are there clouds?
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Read "What Are Clouds Made Of?" by using the forward and back buttons below. |
Chapter 1
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Chapter 2
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Chapter 3
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Chapter 4
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Chapter 5
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Chapter 6
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Chapter 7
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Chapter 8
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What are clouds made of?
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In this activity, you will learn how to identify different types of clouds. |
Engage
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This activity is all about identifying clouds, so let's start by looking at the clouds outside. Look out the window and draw the clouds you see. If there aren't any clouds today, try drawing the different clouds in the photo. Take a snapshot of your drawing. |
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Explore
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cumulus | stratus | cirrus |
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altocumulus | stratocumulus | cumulonimbus |
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Remember that clouds form when air cools. Air usually cools as
it rises higher in the sky.
One reason air rises is that heat from the sun warms the land and water at different rates. The air over the land becomes warmer than the air around it, so a “thermal” forms, a rising section of warm air. As the thermal rises, the air expands and cools. When it has cooled enough, the water vapor condenses into liquid droplets. |
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cumulus cloud |
cumulonimbus cloud |
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Some clouds are low to the ground, about 2.1 km/ 7,000 feet high. Cumulus and stratus clouds are low to the ground because there is not enough energy to push them higher in the sky. |
Some clouds are a medium height, between 2.4 - 4.9 km/7,000 and 16,000 feet above the ground. For medium height clouds, we add "alto" to the name, so these are called altocumulus. Altocumulus clouds form at a medium height because the rising air has more energy. The cooling bodies of warm air that form the altocumulus clouds have risen higher before condensation occurs. |
Some clouds are very high up, over 4.9 km/16,000 feet above the ground. Bodies of air with enough energy to reach this height form clouds of ice crystals due to the extreme low temperature at that altitude. When clouds are very high in the sky, they are called cirrus clouds. |
Explain
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Elaborate
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What is the name of that cloud?
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Engage
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Some of the earth's liquid water is deep under the ground,
in cracks between rocks. We call it ground water. Some
ground water is thousands of years old and some is only a
few weeks old. Ground water comes mostly from rain and
melting snow.
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Explore
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Here is a model showing the water cycle. Run the model and
notice how water travels around and changes from one form to
another.
Click the " run/stop " button to set the model into action. Experiment with the buttons and sliders to see how the model works. When you are ready, go on to the next page. |
This model was created using NetLogo. Go
here
to explore the model on your own.
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Explore
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Use the model to explore the questions below. Take a snapshot
of your model when finished.
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This model was created using NetLogo. Go
here
to explore the model on your own.
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This model was created using NetLogo. Go
here
to explore the model on your own.
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Explain
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Elaborate
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How does water travel around Earth?
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In this activity, you will investigate the humidity over
several simulated environments including oceans, forests,
icecaps, and deserts.
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Engage
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Humidity is a measure of the amount of water vapor in the air. While
water in the air is only a small amount of the Earth's water, our
planet would be very different without it. If the Earth's air didn't
contain water, our weather would be like that of Mars. It would have
no clouds except dust, no rain, no sleet or snow, and no fog.
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An ocean is a large body of salt water. In this activity, you will
use water in a cup to simulate the ocean.
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A forest is an area where most of the plants are trees. In this
activity, you use will grass or plants in a cup to simulate the
forest.
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An ice cap is an area usually covered in ice year round, like the
tops of mountains or at Earth's poles. In this activity, you will
use ice in a cup to simulate an ice cap.
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A desert is an area that has very little rain throughout the year.
In this activity, you will use sand in a cup to simulate the
desert.
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Explore
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Let's start by placing five clear plastic cups in a row. Using
masking tape and a permanent marker, make labels reading
forest, desert, ocean, ice caps, and control. The control
label will be placed on an empty cup so that you can compare
all of your measurements to the air in your classroom.
Now fill each individual cup 1/4 full according to their labels. The control cup will be left empty. |
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Now you need to construct a way to measure the humidity over each environment.
Your teacher will help you cut away the top third of a clear plastic bottle. |
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Remove the cap from the bottle and place the humidity sensor
through the opening of the bottle.
Secure the humidity sensor to the bottle with clay. |
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Explain
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Elaborate
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“Heat islands” are created when growing cities change the
environment by substituting forests with roads, parking lots, and
roofs of buildings. Trees provide shade and cool the air through
evaporation. The hard, dark surfaces like pavement in this picture
store heat during the day, heat that is then released at night,
keeping the city hotter for longer periods of time.
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The city of Chicago is experimenting with a new architecture
they call “green roofs.” On several city buildings they
replaced the black tar surface with soil and plants. The
photo shows the roof of the Chicago City Hall. These green
roofs have worked well to keep the buildings cooler in the
summer.
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What does humidity have to do with clouds?
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In this activity you will explore a computer model that shows how water goes into the air and forms clouds. |
Engage
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The atmosphere consists of many gases including water vapor.
Water vapor is invisible until it forms clouds. And even
though you can't see it, there is dust in the atmosphere. Dust
plays an important role in condensation that forms clouds.
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All matter in the universe is made of very tiny particles,
called atoms. Atoms are grouped in special ways to form
slightly larger (but still very tiny) particles, called
molecules. Suppose you have special glasses and can see the
individual water molecules in a puddle.
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Explore
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This model was created using Molecular Workbench created by
the Concord Consortium.
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In the model, the left side represents a LIQUID . The molecules slither and slide around, but stay close to each other. |
In the model, the right side represents a GAS . The molecules are far apart and are moving very fast all the time. They bounce off each other. |
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This model was created using Molecular Workbench created by
the Concord Consortium.
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This model was created using Molecular Workbench created by
the Concord Consortium.
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You probably noticed that when the gas on the left side is
cooled down, the molecules clump together because they aren't
going as fast. This is called condensation. This is what
happens when water vapor forms into water droplets.
When these "clumps" are big enough, we can see them as water droplets. That's what fog and clouds are -- water droplets in the air. The water droplets are usually so small that they float in the air. And when they are big droplets, they can fall as rain! |
Explain
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This model is slightly different than the last one. It has a
temperature slider.
Run the model and experiment with the temperature slider. Take snapshots at different temperatures and note the differences in your Lab Book. |
This model was created using Molecular Workbench created by
the Concord Consortium.
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Elaborate
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This model was created using Molecular Workbench created by
the Concord Consortium.
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How are clouds formed?
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Have you ever heard a weather forecaster say, "Today it will be partly cloudy"? How many clouds does it take to be partly cloudy? In this activity, you will develop a method to calculate cloud cover in the sky. |
Engage
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Percent Cloud Cover Table
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Explore
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Now take your
own
measurement of cloud cover. First set
up your mirror.
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Percent Cloud Cover Table
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Explain
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Elaborate
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How much of the sky is cloudy?
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Why are there clouds?
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Now it's time to review and summarize what you have learned
about clouds. To help, you can show all of your snapshots and
some of your written answers from the activities. They are all
in your Lab Book.
Review the questions on the following pages. There is a separate page for each activity that you worked on. Be prepared to share your answers with the rest of the class. |
Story: Wondering about clouds
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Water cycle model
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Making clouds
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Cloud detectives
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Humidity
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Cloud cover
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Summary
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Wrapping up
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What have you learned about clouds?
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