This activity will demonstrate the formation of condensation and will show that there is water vapor in the air even though it is not visible.

Time requirement: 20 minutes as an activity, 15 minutes as a demonstration.



  1. Fill each beaker with equal amounts of water. Be sure to leave enough room to add ice.
  2. Record the temperature of the water.
  3. Add one ice cube at a time to one to the beakers. Stir with the stir stick.
  4. Continue to add ice to the one beaker and stir until moisture appears on the outside of the beaker.
  5. Record the amount of time required and the temperate of the ice water.

Observation questions

  1. Why does moisture appear on one beaker and not on the other?
  2. Where did the moisture come from that appeared on the side of the beaker?
  3. What was the difference in temperature between the two beakers?
  4. Why do you sometimes observe dew on the grass when you leave your house in the morning?
  5. In certain areas (like the Pacific Coast where Stanford is located) fog forms overnight and "burns off" during the morning hours. Why does this happen?

Last updated: September 04, 1997
Joe Twicken /
Rob Wigand