Here’s a simple homemade barometer you can use to introduce your children to weather forecasting.
Hands-on science is the best kind of science. After you and your children make this homemade barometer, you will understand more about air pressure and how it affects the weather.
What’s a barometer and how is it used to forecast weather?
A barometer is an instrument that measures air pressure. An area with lower pressure than the surrounding areas usually predicts wind and rain.
When the air pressure is up, this usually forecasts good weather.
You might want to do this activity on a day of average barometric pressure.
Materials Needed to Make Your Homemade Barometer
- An empty can
- a balloon
- a rubber band
- a straw
- a straightened paper clip
- printable weather chart or ruler
1. Cut the nozzle off the balloon. Stretch the balloon over the opened end of the can and secure it with a rubber band.
2. Tape the straw to the middle of the can and insert the paperclip into the end. My paper clip was too large for the straw so I had to bend it with a pliers to get it the right shape. The goal is to have the paperclip fit snugly inside the straw.
3. Set the can somewhere where it will not be disturbed.
4. Hang the weather chart so that the paper clip is pointing at the center line. You can also use a ruler for this.
5. Observe the position of the needle each day. You may wish to record the pressure twice daily for seven days. You can download the barometer tracking sheet for this.
6. A rise in the needle forecasts sunny weather. A fall in the needle forecasts clouds and wind.
How does the homemade barometer work?
When you first assemble the barometer, the air pressure inside and outside the can are equal.
As the air pressure outside the jar falls, the air inside the can will expand. This pushes up on the balloon causing it to bulge. As a result, the end of the needle falls.
When the air pressure outside the balloon rises, it puts pressure on the air inside the can. The air outside pushes on the top of the balloon causing the needle to rise.
When we made this, I wasn’t sure what to expect, but the little pointer moved down on the ruler over the next few days. Sure enough, clouds, wind and rain moved in. It’s even neat for me as a mom to experience science firsthand.
For more nature activities like this one, check out my “Month in Nature” calendars.
This post is part of a 10 Day Learning with Nature Series. If you enjoyed this activity, you might want to take a look at the other posts in the series.