A clean, clear 2 liter plastic bottle for every 3 students
A box of wood matches for every 3 students
A thermometer for every bottle (available at fish stores)
An eye dropper or other container for water
a. Prior to the activities
What makes air warm? What happens to warm air?
What makes air cold? What happens to cold air?
What are clouds? How are clouds made?
What 3 things are necessary to form clouds?
What is fog?
b. After the activities
Have students answer this question in writing: In your own words explain what we did in these two activities. What do you know about the relationship between air temperature, air pressure, condensation, and the formation of clouds?
It is recommended that these activities be carried out over two class sessions. The first session is part 1 and second session is part 2.
Session 1: Temperature changes in a closed soda bottle Tell students that they will work in groups of 3.
Each group will have:
1 clear plastic bottle with cap
1 temperature strip
1 strip of tape
1 Box of Matches
1 paper on which to record their data
The first step :
Tape the temperature strip into the bottle so that you can read it. Then screw the bottle cap on tightly. Lay the bottle on its side so you can easily read the temperature strip.
Read and record the temperature of the air inside the bottle. Then use both hands to squeeze the bottle as hard as you can. After about 1 minute read the strip. Then stop squeezing and read the temperature strip after about 1 minute.
What happened the temperature when you squeezed the bottle?
What happened to the temperature when you stopped squeezing the bottle?
Session 2: Making a cloud-in-a-bottle
Open the bottle and pour in a few drops of water. Screw the bottle cap on tightly. Swirl the water around the inside of the bottle so that most of the inside of the bottle is wet. Squeeze the bottle and observe the temperature again. What happened?
Lay the bottle on it's side, open the bottle, and push down to flatten the bottle to about 1/2 it's normal size. Have someone light a match, blow it out, and put the match into the bottle while it is still smoldering. Quickly release the sides of the bottle and put the cap on tightly. Now squeeze the bottle as before very tightly for about 1 minute. Quickly let it pop open.
What happens? Hopefully, you should be able to see a cloud. In this experiment you saw water molecules condense into a cloud in the bottle. When you squeezed the bottle the air pressure in the bottle increased which raised the temperature. The warmer air caused the water in the bottle to evaporate (it became water vapor) and you could not see it. When you let the bottle pop out the air pressure in the bottle was lowered and so was the temperature. This caused the water molecules to condense into a cloud