Cloud in a Bottle
Summary: Students are introduced to condensation, evaporation, and water vapor and how
they relate to the water cycle.
California Academic Standards:
5th grade - Earth Sciences
3.b. Students know when liquid water evaporates, it turns into water vapor in the air and can
reappear as a liquid when cooled or as a solid if cooled below the freezing point of water.
3.c. Students know water vapor in the air moves from one place to another and can form fog or
clouds, which are tiny droplets of water or ice, and can fall to Earth as rain, hail, sleet, or snow.
Tools and Equipment:
1.
2.
3.
4.
An adult to help
Clear plastic two liter bottle with cap (soda bottles work best)
Matches
Warm water
Directions:
Part 1
1. Fill one-third of the plastic bottle full of warm water and put the cap on.
Question: What happened?
Answer: The inside becomes covered in condensation because as warm water evaporates it
adds water vapor to the air inside the bottle.
2. Shake the bottle to get rid of the condensation, do this as often as you need to in order
to see what’s happening inside the bottle.
Part 2
1. Squeeze the bottle as hard as you can for one minute.
2. Release and see what happens.
Question: What happened this time?
Answer: Nothing! Even though you can’t see what’s happening, squeezing the bottle is like
the warming and higher air pressure that occurs in the atmosphere; releasing is like the cooling
and lower air pressure that occurs in the atmosphere.
Part 3
1. Unscrew the cap.
2. Have an adult light the match and hold it near the opening of the bottle.
3. Drop the match in the bottle and quickly put on the cap, trapping the smoke inside.
4. Slowly squeeze the bottle as hard as you can for one minute.
5. Release.
6. Repeat steps 4 and 5 as much as you’d like.
Question: What happened? (You should be able to see a cloud).
Answer: A cloud appears when you release the bottle and disappears when you squeeze it. A
cloud needs 3 ingredients to form:
1. Water vapor
2. Dust, smoke or other particles in the air
3. Drop in air pressure
Water vapor, water in its invisible gaseous state, can be made to condense into the form of
small cloud droplets. By adding particles, like the smoke, enhances the process of water
condensation and not squeezing the bottle causes the air pressure to drop.
With a partner, answer these questions:
Liquid water evaporates and becomes water vapor (note how the terms are similar). Water
vapor cannot be seen. When water vapor rises into the atmosphere it becomes clouds and you
can see them. What are clouds made of?
Answer: There is always water vapor in the air, but when enough water vapor comes together
through the correct air pressure, clouds are formed.
Now that you know how clouds form, how do you think rain forms?
Answer: If the clouds are big enough and have enough water droplets, the droplets join
together and get even bigger. When the drops get heavy enough, they fall because of gravity
and that’s when you see and feel rain.