How to Make a Barometer

Recently I had to make a barometer. To do so I needed a glass jar, a balloon, tape, scissors, and a straw. I cut the balloon in half and placed it on top of the glass jar. I taped the straw to the middle of the balloon and then cut the end of the straw off at an angle.

When the pressure on the outside of the jar is more than the pressure on the inside it will push down on the balloon and cause the straw to go up. 

If the pressure on the inside of the jar is more than the pressure on the outside then the pressure on the inside will cause the balloon to bulge and the straw will point downwards. 

Here are a few videos on how to make different versions of barometers.

How to Make a Weather Barometer

How to make a Barometer

Weather Barometers: How to Make a Barometer