Cloud in a Glass: The Science of Water Vapor Condensation
Time needed: 15 minutes
Difficulty level: Easy
Age range: 6+ years
Adult supervision: Required for hot water handling
Difficulty level: Easy
Age range: 6+ years
Adult supervision: Required for hot water handling
What You'll Learn
This experiment demonstrates how clouds form in our atmosphere through the interaction of warm and cold air. You'll create a miniature version of this natural process, making real clouds appear and disappear in a glass jar.
Materials Needed
Materials collected: 0/6
Large clear glass jar
Hot water
Blue food coloring
Optional
Ice cubes
Plate or shallow dish
Hairspray or matches
Choose one
Safety Notes
Be careful handling hot water
Adult supervision needed when using very hot water
Keep electronics away from water
If using hairspray, spray in a well-ventilated area
If using matches as an alternative to hairspray, this must be done by an adult only
Step-by-Step Instructions
1
Pour about 2 inches (5 cm) of hot water into the glass jar
Optional: Add a few drops of blue food coloring to make the water look like an ocean
Watch the steam rising - that's water vapor forming!
2
Place the plate or shallow dish on top of the jar
Wait 30 seconds for the jar to fill with warm, moist air
3
Put 3-4 ice cubes on the plate
Watch what happens where the warm air meets the cold plate
4
Optional: Add condensation nuclei
Either spray a quick burst of hairspray into the jar
OR have an adult add match smoke (light match, blow out, add smoke)
5
Watch your cloud form!
Remove the plate to see the cloud escape upward
Watch It In Action
See this experiment demonstrated step by step in this video. The video shows the hairspray method. Pay special attention to how the cloud forms at the top of the jar and how it falls when the plate is removed.
The Science Behind It
When warm air rises and meets cold air, the water vapor in the warm air condenses into tiny water droplets.
The warm water in your jar creates water vapor (water in gas form).
When this warm, moist air hits the cold plate with ice, it cools quickly and condenses into visible water droplets - your very own cloud!
Common Questions
Why isn't my cloud forming?
Make sure your water is hot enough and you have a good seal with the plate.
Why does hairspray or match smoke help?
They both provide particles for water to condense around, just like dust particles in the atmosphere.
Which works better - hairspray or match smoke?
Both work well as they both provide condensation nuclei. Hairspray is recommended for safety, especially with children, but match smoke can also create clear results when used by adults with proper precautions.
Can I use other containers?
Yes, but glass works best because you can see through it clearly.
Why do some people add blue food coloring?
The blue coloring is just for visual effect - it makes the water look like an ocean at the bottom of the jar. The dye stays in the water and doesn't affect the cloud formation process. Your cloud will still be white/gray regardless of the water color.
Take It Further
- Try using different temperatures of water
- Compare results with and without condensation nuclei (hairspray or match smoke)
- Time how long your cloud lasts
- See if the cloud behaves differently in warm vs. cool rooms
Related Experiments
If you enjoyed this experiment, try these next:
- Colorful Density Layers - Another experiment exploring temperature effects
- Frost Formation - Explore crystal formation during freezing
