What is air pressure? Did you know you can make something that will measure air pressure? You can actually do a bit of weather predicting from a simple made-at-home piece of equipment.
What do I Need?
An empty coffee can
A large balloon
A large rubber band, one that will fit snugly around the coffee can
What Do I Do?
First, as an experiment, blow up the balloon. Think about how the more air there is in the balloon, the more pressure it exerts outward. This is what makes the balloon bigger as you blow it up.
Cut a large piece of the balloon and stretch it over the coffee can. Hole the balloon in place with a rubber band stretched around the can, over the balloon. Make sure there is a tight seal around the rubber band. Any air leaks around the piece of balloon will affect how well your barometer will work.
Use a little glue (not hot melt) and attach the straw to the piece of balloon over the can. Then use a little more glue and attach the pin to the other end of the straw (see diagram.)
Take a piece of paper and place some regularly spaced lines on it.
Set up the can and paper as shown in the diagram. Outside will work better than inside.
Using Your Barometer
Make several daily recording for about a week. Make notes about the weather when you take the readings. What do you notice about the readings and the weather? Compare the readings of the barometer outside with those of a barometer inside.
How Does It Work?When air pressure increases, it exerts more pressure on the balloon, pushing it down and the pin upwards on the scale. When the air pressure decreases, the pressure lessens on the balloon and a lower reading is recorded.
In general, low air pressure means rainy or cloudy weather. When the barometer drops, a storm may be approaching. High air pressure usually indicates clear weather.