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A homemade barometer allows kids to play meteorologist and get a little understanding of how changes in air pressure can help forecast short term changes in weather. This simple little contraption will allow kids to observe changes in barometric pressure and make some weather predictions of their own!
How to assemble
- Cut the neck off a deflated balloon.
- Stretch the rest of the balloon over the mouth of a large jar, pulling it perfectly flat and taut. Secure it with one or two rubber bands.
- Fold the end of one straw and insert it into the end of another, securing with a bit of tape. Cut a tab and flatten one end.
- Cut a paper arrow and insert it into the opposite end of the straw. Make sure the arrow is cut so the straight edge fits snugly into the straw.
- Secure the straw’s tab to the centre of the balloon with a dab of white glue. (Tape it in place for extra security until the glue dries).
Now set your new barometer against a wall, out of direct sunlight, in a place it won’t be disturbed. Place a chalkboard or piece of paper behind it, marking a line where the arrow is level, with a few lines above and below. See below for guidance.
How your new barometer works is that the air pressure inside the jar will stay constant, while the air pressure outside of the jar will change.
When the barometric pressure falls, the pressure inside the jar will be higher causing the balloon to bulge and as a result, the arrow will drop pointing to approaching unsettled weather.
When the barometric pressure rises, the lower pressure inside the jar will make the balloon sink and cause the arrow to rise, indicating that sunny spells are on the horizon!