How to Make a Barometer with a Jar and Balloons

Creating a barometer is quick and easy with nothing more than a glass jar, a balloon, an ordinary drinking straw and some rubber cement. The results will provide you will a handy tool for recording changes in air pressure that will tip you off to incoming weather fronts. High pressure readings indicate fair weather with little or no precipitation. A low reading suggests cooler weather with a chance of precipitation on the way. Your friends will be amazed by your new ability to predict weather patterns with something as simple as a homemade barometer from common household items!

Difficulty: Easy

Instructions

Things You'll Need:

• Glass jar (small mouth)
• Drinking straw
• Balloon
• Rubber band
• Rubber cement
• Paper and pencil

1. Take an ordinary drinking straw, not the flex type, and flatten a section 1-inch long on one end. With a sharp pair of scissors, carefully clip a diagonal line from the tip of the flattened end to the end of the fold. This will create a 1-inch tip that resembles a quill.

2. Color the tip using a fine tip marker. This is the pointer used to measure pressure and should be easy to see.

3. Cut the balloon in half and stretch it over the mouth of the jar so that it is taut. Secure it with a rubber band.

4. Apply rubber cement in a strip from the center of the balloon to the edge of the jar.

5. Place the drinking straw on the rubber cement with the uncut end in the center and the quill pointed outward. The quill should extend about about 6 inches past the rim of the jar, perpendicular to the top of the jar. Hold the straw in place until the glue dries.

6. Mark a sheet of paper at regular intervals to keep track of changes in atmospheric pressure. Tape the paper to the wall near a stand or shelf you intend to display the barometer on.

7. Place the barometer near the paper so that the pointed end of the straw nearly touches the paper. Mark the point where the straw rests. Add a time and date to the reading.

8. Record your readings on a daily basis and watch the pressure change according to the air pressure. You may want to watch the weather channel for a few days to get a good idea of what your readings really mean. Jotting down the atmospheric pressure reported for your area next to your readings will give you basic number readings for your chart.