Measuring Air Pressure With Your Own Barometer
Materials Needed:
Wide-mouth jar, can or cup
Balloon or good plastic wrap
Strong rubber band
Tape and/or glue
Drinking straw
Pin or needle (optional)
Paper
1. If using a balloon, first cut off the neck. Stretch the balloon or the plastic wrap across the mouth of the container you are using, and secure in place with the rubber band. If using plastic wrap, make sure that it is taut and smooth across the mouth. Optional: You can further secure the wrap with wide tape such as masking tape, packing tape or duct tape. (Optional: I also placed a little weight in the bottom of the cup I used, as it was very light-weight and I didn't want it to tip over at the drop of a hat.)
2. For more precise measurements, you will want to tape or glue a pin or needle to one end of the drinking straw. If you're only looking for a general idea of the changes in air pressure, you can skip this step. If you decide to use glue for this step, do so at least an hour before beginning to assemble the barometer.
3. Tape or glue the other end of the straw to the middle of the balloon or plastic covering your container. Be careful not to mash too hard so as not to disturb the tightness of the balloon/plastic wrap.
4. Prepare your measurement paper. There are two options:
| A. Mark off a set of measurements of your choosing. In the illustration, I have 15 centimeter marks in black, with half-centimeter marks in red in between. The marks are labeled from bottom to top. You can then note your barometric changes by the numbers that you have chosen for yourself. B. Prepare your paper so that it is easily removable from the barometer set-up, or easy to write on while it stays in place. (If you choose to move it in order to be able to write on it, you will need to put it back in exactly the same place each time.) At different times, make a mark where the needle is resting on the paper, then check your local weather on the internet, making a note on the paper what the official barometric pressure is at that moment. Over time, you will have a set of marks that will allow you to take readings of your own that should closely match the official readings. |
5. Set up your barometer and measurement paper on a shelf or counter that is not too close to a window or door, as changes in temperature will affect your barometer's readings. Give your barometer an hour or so before trying to take any readings.
You can use the chart below to observe for your barometer for one week, noting the changes. Try to take your readings about the same time of day, every day. Make notes of the weather that accompanies the changes in readings; if you continue the chart for several weeks, see if you can start seeing patterns in the readings and the resulting weather that will allow you to predict what sort of weather is coming your way.
| Barometer Reading | Weather Observations | |
| Day 1 - Morning | ||
| Day 1 - Afternoon/Evening | ||
| Day 2 - Morning | ||
| Day 2 - Afternoon/Evening | ||
| Day 3 - Morning | ||
| Day 3 - Afternoon/Evening | ||
| Day 4 - Morning | ||
| Day 4 - Afternoon/Evening | ||
| Day 5 - Morning | ||
| Day 5 - Afternoon/Evening | ||
| Day 6 - Morning | ||
| Day 6 - Afternoon/Evening | ||
| Day 7 - Morning | ||
| Day 7 - Afternoon/Evening |
