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How to Make a Cloud in a Jar

Clouds in the Earth's atmosphere consist of water vapor that condenses into visible water droplets. Sufficient condensation causes rain when the weather is warm or snow when temperatures are cold. The water vapor forms clouds when it has nucleation sites, which are points of condensation on which to collect, in the atmosphere. Observe the same mechanism that causes water vapor to condense into clouds with a small-scale experiment that uses household items.

Things You'll Need

Lidded glass jar
Black paper
Tape
Hot water
Ice
Matches
Flashlight (optional)

Instructions

- 1
  Tape a section of black paper to the back of a jar, leaving about half of the jar uncovered as a window to the interior. The dark surface will make the small cloud more visible when it forms.
- 2
  Pour about an inch of hot water into the jar. Use a jar that is already at room temperature or above to prevent thermal shock from cracking the glass.
- 3
  Swirl the water in the jar to warm the sides of the vessel and wash away any immediate condensation.
- 4
  Upend the lid of the jar and use it as a shallow dish for the ice. Fill the lid with ice and set it atop the jar's opening.
- 5
  Strike a match and blow it out. Quickly lift the lid from the jar and toss the spent and smoking match into the jar, then replace the lid.
- 6
  Observe the interior of the jar and look for water vapor to condense into wisps of cloud on the smoke particles from the burnt match. Use a flashlight to illuminate the inside of the jar if the tiny clouds seem hard to see despite the black paper backing.

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