CLEAR DAY, CLOUDY DAY
Physical Science: Making Clouds in the Classroom
Background: Unclogging the Issue
Throughout time and across cultures, people have looked to the sky for clues about approaching
weather. Even young children know that clear, sunny skies mean good weather with little likelihood
of rain or snow, while ominous, dark clouds warn of precipitation and winds.
Data from satellites monitoring cloud cover is used to more accurately predict weather changes,
especially precipitation. We get a computerized view of clouds from above and an appreciation for
the predictions they make possible. Identification of specific cloud types can add even more
precision to weather predictions.
Stratus clouds are among the closest to the Earth. These gray, shapeless layers often look like soft
sheets across the sky. They mostly produce drizzle.
Cumulus clouds look like puffy cotton balls with flat bases. Though usually indicative of fair weather,
these cloud formations can merge to produce precipitation.
Cumulonimbus clouds are dark gray, towering, and imposing. Commonly referred to as
thunderheads, these clouds can produce thunderstorms and heavy rains.
Cirrus clouds are so high that their moisture takes the form of ice crystals. These feather wisps are
always white, rather than gray, because the sun's rays are reflected by the ice crystals they hold.
They often appear before a change in weather.
Opening Discussion: Look Up
To start students thinking about clouds, take time to go outdoors and look
at clouds, if weather permits. Estimate the height of the clouds in feet and
meters, and see if students can find unusual shapes. Encourage them to
record their observations in writing or with pictures. Keep these for later
use.
Activity: Reaction Time
Overview: Students simulate cloud formation within a bottle.
Materials: empty 2-liter soda bottle, hot water, black paper, ice cube
What to do:
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Fill the bottle with hot water and let it stand for several minutes.
Carefully pour two-thirds of the water out of the bottle.
Place the bottle in front of the black paper.
Set the ice cube on the neck of the bottle. Have students observe
the results. Explain that when the warm, moist air within the bottle
rose up to meet the icy air near the top, the water vapor
condensed to form a cloud. The same reactions occur every day
to create cloud formations.
Note: Ask students to explain the use of black as a background color for
this exercise. Guide them to realize that scientists try to create the best
conditions for observing the results of their work.
Assessment
Talk about the cloud formations the class observed outdoors. Challenge
the students to identify the type of clouds they saw by using the information
in the Background section and available resource materials. Then have
volunteers repeat the Test Flight experiment, using water and weather
terms to explain each step. Encourage them to relate the process to the
formation of real clouds including such factors as air temperature,
evaporation, water vapor, condensation, and relative humidity.
Career Studies: With an Eye on the Sky
Many people have careers that are affected by, or even dependent upon,
cloud conditions and the weather they signal. Have students work in small
groups to create a matrix relating jobs to cloud conditions and their
associated weather. The side column should list a variety of careers, while
the top row should identify a number of weather conditions. Working
together, students can use +, -, or = to indicate which types of clouds and
weather have a positive, a negative, or little effect on the ability to perform
each job. Have students show and explain their charts to the class.