Concepts:
Principles:
- Weather activity happens when wet air goes up into the atmosphere and
cooler air comes down from the atmosphere.
- One cause of rising air in our atmosphere is from the process called
convection.
- Warm air rises above cold air by convection.
- Clouds form when water vapor condenses and molecules cling to each
other.
- While convection is happening and warm moist air is going upwards, there is
also the sinking of denser and cooler molecules from the sky moving
downward.
Facts:
- Convection happens because warm air is less dense than the cold air around
it, so it is lighter and rises or goes up in the atmosphere.
- Evidence of convection happening is seen with the formation and growth of
cumulus clouds.
- We see evidence of sinking motions of heavier and cooler air falling to the
earth when the sky is clear or without clouds.
- Warm and moist air rises and forms clouds in our sky.
- There is a constant balancing act going on all the time in our atmosphere
as moist, warm air goes upward and cooler, denser air moves down. Air is
constantly moving upward and downward, creating our "weather."
Skills:
- Following directions
- Making observations
- Making inferences
- Drawing conclusions
- Forming generalizations
- Communicating findings
Materials
- Large glass jar without a lid
- Small glass jar with a lid (which fits inside larger jar)
- Plastic drinking straws
- Dark food coloring
- Hot water in large pouring container
- Cold water in large pouring container
- Hammer and large nail to make holes in lids of small jars
- Scissors to cut straws into 2-inch pieces
- Rulers
- Pen
- Paper towels or sponge
- Handout
Room Preparation
Water activities are often messy activities! Each student (or pair) needs a
work area in which to do their own experiment. Water is likely to spill, so
remove any materials that should not get wet from tables or desks. Also,
have paper towels or sponge ready to clean up tabletops and floors.
Safety Precautions
If students use hammer and nails to make two holes in their small jar lids,
review safety rules and how to make holes. Exercise caution and review
safety concerns when students fill small jars with hot water. Remind
students to be careful when adding food coloring drops to small jars. Food
coloring may stain clothes.
Procedures and Activities
Introduction
What do we see when we look up into the sky? Sometimes we see a mass of
clouds, sometimes some clouds and some clear sky, and sometimes nothing but
clear sky everywhere.
Today, we are going to do an experiment to help us understand:
- What is convection?
- How does convection happen in our atmosphere?
- How do clouds form?
- What makes the sky clear or without clouds?
Activity
- Pass Out Materials
Provide each student or pair with large jar, small jar with lid (you may
have already punched two holes in lids), plastic straw and scissors. If
students punch holes in lid, you will need to give them a hammer and a
large nail.
- Make 2 Holes in Small Jar Lids or Pass Out Lids Already with
Holes
Show students how to use the hammer and large nail to carefully punch 2
holes in the lid of the small jar. These holes should be just large enough
to hold a piece of the straw snugly. Be careful not to make holes so large
that the straws fall through.
- Cut Straws into Two 2-Inch Pieces
Have students use ruler and pen to measure and mark straw to make two
2-inch pieces. Have students cut on marks. Set aside straw pieces.
- Put Straws into Lid Holes
Students put one piece of straw in each hole. One piece of straw should be
placed so that about half an inch is above the top of the lid. The other
straw piece should be placed so that about half an inch is below the lid.
- Food Coloring in Small Jar
Have students put a few drops of dark food coloring in the small jar.
- Hot Water in Small Jar
Pour or have students pour hot water into small jar until it is full. Screw
on lid of the jar. Make sure 2 straw pieces are properly placed. Put small
jar aside.
- Cold Water in Large Jar
Pour or have students pour cold water about 3/4 full in the large jar.
Remind students that they will put small jar in large jar. Go over water
displacement—if large jar is full of water, when we put small jar in
it, the cold water will rise and spill out.
- Place Small Jar of Hot Water into Large Jar of Cold Water
Carefully place the small jar into the big jar. Be sure the cold water
completely covers the top of the higher straw. If not, add some cold water
to large jar until straws are covered.
- Observations, Drawing Conclusions & Forming Generalizations
Carefully observe what is happening. Where is the colored water from the
small jar of hot water going? What happens to the colored water when it
reaches the top of the small jar? What happens when colored water gets out
of small jar and into the cold water of the large jar?
- Communicating Findings
Have students take time out to draw and answer questions found on the
handout. Have them work in pairs or small groups to prepare a summary of
what they did and what they think happened. Share that this process is
"communicating findings": a very important part of a scientist's job, so
she or he can tell others what they did and what they think they found out.
Closing - Original Questions
Ask again:
- What is convection?
- How does convection happen in our atmosphere?
- How do clouds form?
- What makes the sky clear or without clouds?
Evaluation
Have students take turns sharing with each other:
- What our original questions were
- What experiment we conducted
- Our observations and findings
- And finally, our answers (conclusions & generalizations) to the original
questions
Extension Ideas
Have students repeat their experiment to make sure that their observations,
findings, generalizations, and conclusions are accurate. Share that
experiments have to be replicated many times to be sure that findings are
true. Review the importance of following directions precisely so you do not
change or alter variables that may, in turn, change the experiment's results.
Let students come up with similar experiments which do purposefully alter
variables. For example, they may put hot water in large jar and cold water in
small jar. Have them document just what materials and steps they followed,
what they observed, and what their conclusions and findings are. Then they may
compare the two experiments and results, offering explanations for
similarities or differences in their findings.
Explore Images
and Animations Illustrating Convection from the Jet Propulsion Lab.
Look over other activities from CAPS: Does the Sun
Influence the Temperature of the Earth?, Reading a Thermometer, Keeping a
Daily Weather Log, What Is Heat Transfer?,
and What is Temperature?
Careers Related to the Lesson Topic
- Aerospace Engineer
- Tour
- Aerospace Labs and Wind Tunnels
- Anyone with a Job Outdoors
- Environmentalist
- Environmental Engineer
- Farmer
- Meteorologist
- Tour,
Weather Underground at University of Michigan's Department of
Atmospheric, Oceanic, and Space Sciences
- Naval Science & Engineering
- Pilot
- TV or Radio Weather Reporter