Make and Use a Barometer to Measure Air Pressure
Overview
Air pressure is the result of the weight of tiny particles of air (air molecules) pushing down on an area. While invisible to
the naked eye (i.e. microscopic), they nevertheless take up space and have weight.
For example, take a deep breath while holding your hand on your ribs and observe
what happens. Did you feel your chest expand? Why did it expand?
Air pressure expands because the air molecules take up space in your lungs, causing your
chest to expand. Furthermore, air can be compressed to fit in a smaller volume since there's a lot of
empty space between the air molecules.
When compressed, air is placed under high pressure. Meteorologists measure these
changes in the air to forecast weather, and the tool they use is a barometer.
The common units of measurement that barometers use are millibars (mb)
or inches of mercury.
Make a Barometer
(if you already have a barometer, you can skip to the
Use a Barometer to measure Air Pressure)
- Materials
- wide-mouthed glass jar or small coffee can
- balloon (recommended) or plastic wrap
- rubber band
- scissors
- drinking straw
- cardboard strip
- glue (recommended) or tape
- ruler and pen or pencil
- small piece of modeling clay
- shoe-box sized cardboard box
|
 |
- Procedure
- How does this measure air pressure?
High pressure will make the balloon seal dip causing the straw go up. Low
pressure will make the balloon puff up causing the straw to go down.
Use a Barometer to measure
Air Pressure
- Materials
- Procedure
- lace the completed barometer and scale in a shaded location free from
temperature changes (i.e. not near a window as sunlight will adversely
affect the barometer's results).
- In your notebook or the table below, record the current date, time, the
weather conditions, and air pressure (i.e. the level where the end of the
straw measures on the scale).
- Continue checking the barometer twice a day (if possible) each day over
a period of several weeks.
Data Table
Date |
Time |
Weather
Conditions |
Air
Pressure |
|
|
|
|
|
|
|
|
|
|
|
|
|
Sample Data Table
Date |
Time |
Weather
Conditions |
Air
Pressure |
June 4, 2003 |
9:30 am |
Clear and Sunny |
4 |
June 4, 2003 |
2:30 pm |
Cloudy |
3 |
June 5, 2003 |
9:30 am |
Rainy |
1 |
|
Copyright © 2007 Stevens Institute of Technology,
Center for Innovation in Engineering and Science Education (CIESE) All Rights Reserved.