# How a Homemade Barometer Works

A barometer is a tool that meteorologists use to predict weather patterns. Generally speaking, low pressure systems will indicate rainy and cloudy weather while high pressure systems will show cool and dry conditions. You can learn about the various types of weather patterns by learning to make your own homemade barometer, which will allow you to watch the air pressure around you and track how it changes over time.

#### How a Homemade Barometer Works

To begin this investigation, you will need some glass jars and balloons. You can find a variety of sizes of these items at any hobby store or craft store.

1. Set the jar on a flat, straight surface (either a table or floor). If you are working with younger children, have them sit at a desk to avoid injury while they work.

2. Cut a length of balloon about two inches larger than the mouth of the jar and tie it securely to the jar with a rubber band. This will prevent the balloon from suffocating the child or if they are small, have an adult hold it while it is tied to the jar.

3. Cover the top of the jar with plastic wrap or latex. This is important because the jar will be sealed off at the top when you seal it.

4. Place the jar over the balloon and secure it in place with the rubber band.

5. Now place the straw over the opening of the jar.

6. If the straw points up with rising pressure, the jar is high. If the straw points down with falling pressure, the jar is low.

7. Mark the location of the straw on a card or paper.

If you are using this activity with older students, ask them to make a graph of the barometer readings. They can then explain to the class what different pressure values mean.

8. Have them measure the pressure inside their jar and outside their jar every day.

This helps to develop their ‘Gather and interpret data’, ‘Use evidence’ and ‘Critique evidence’ skills. They can also discuss how their data may have been affected by factors such as wind or humidity.

9. Conclusion: As the pressure changes, the liquid will be pushed down into the lower container. Depending on how much air is pushed into the lower container, the upper container will also change in size and shape.