Make a Barometer

This activity will give students an opportunity to make their own barometer and to observe changes in the local weather.

Time requirement: 40 minutes as an activity, 20 minutes as a demonstration.

Materials

Procedures

  1. Stretch the balloon tightly over the top of the container. Make sure that the container is at room temperature.
  2. Tape the edges of the balloon to the side of the container making an air-tight seal.
  3. Place a drop of glue onto the middle of the balloon and glue one end of the popsicle stick there. Allow the other end of the stick to extend over the edge of the container. Allow the glue to dry.
  4. Stand the 3x5 card on end (or attach the card to the side of the container) next to the end of the stick which extends over the edge of the container. Mark the position of the stick on the card.
  5. As the air pressure changes, the stick will respond by moving up or down relative to the original mark.
  6. Make observations of the air pressure for a number of days by marking the position of the stick each day. Correlate the position of the stick with readings from a calibrated barometer or with weather data from a local newspaper.
  7. Temperature changes will also cause the stick to move, so be sure that the room temperature is constant with each observation.

Observation questions

  1. Does the stick move up or down with an increase in air pressure?
  2. What happens to the balloon with an increase in air pressure?
  3. Why does the stick move in the other direction with a decrease in air pressure?
  4. Why is the room temperature so important to this activity? What happens to the stick if the room temperature changes?
  5. Will the barometer work if the balloon is not sealed air-tight?

To think about

If you have ever driven into the mountains with a sealed bag of food, you will surely have noticed that the bag expands like a balloon at high altitude. Why does this happen? What would happen if you brought your home-made barometer to high altitude???


Last updated: August 26, 1997
Joe Twicken / joe@nova.stanford.edu
Rob Wigand