Atmospheric pressure or the pressure exerted by the weight of air above the earth’s surface is measured by a barometer. A barometer uses mercury, air or water to measure atmospheric pressure. Its invention in mid-sixteenth century was credited to Evangelista Torricelli. A mercury barometer consists of a glass tube about thirty-three inches long filled with mercury. This tube is inverted over a chamber that is also filled with mercury. An aneroid barometer on the other hand uses a sealed chamber with a pointer. It is possible to make an aneroid barometer using things you have in your kitchen. Below are the steps on how to make your own barometer.
- Get a glass jar, a squat round can, like a cat food can or a cup with wide mouth. You also need water (optional), an eight to nine-inch long bamboo skewer, a twelve-inch round balloon, rubber bands, glue, tape and scissors, a piece of cardboard and markers.
- If your canister, can or jar is light and may topple down once the skewer is attached to it, place some water into the container to make it steadier. If your jar is stable and heavy there is no need to add water.
- Cut the tapering end of the balloon, slightly above the thin and long part of the balloon. Stretch the wide part of the balloon over the jar. The edge of the balloon should reach about halfway down the side of the jar. Skip a rubber band or two over the side of the jar and wrap it tightly around so that the balloon will not be released when pressure builds up and to prevent air from entering the jar.
- Place glue on the blunt end of the bamboo skewer. Position this at the center of the balloon, which is over the cup. Secure it in place with tape until the glue is completely dry.
- While waiting for the glue to dry, you can prepare the gauge part of the barometer. Cut the cardboard to about five inches wide and seven inches long. If you are using a printed cardboard cover it with white bond paper.
- Place the jar on a counter near a wall and position the cardboard on the wall. The pointed end of the bamboo skewer should be pointing to the cardboard. Move the cardboard slightly upward so that its top half is beyond the height of the jar. Tape the cardboard gauge to the wall. Mark the spot where the pointer is located. Take a look at the weather outside and note it on the card beside the mark that you have made.
- Check your homemade barometer daily. If the pointer is above your initial mark, it means that the pressure is rising. It the pointer is below your mark, the pressure is going down. You can place a small notebook beside your barometer to make a record of your readings. You can also place marks on your cardboard gauge to indicate significant pressure build up or down.
Learn how to read the barometer so you can make your weather predictions. When the pointer of the barometer is over your median and continues to go up it means that the weather will be better. If it is below your median, the pressure is lower. When it steadily moves down, you can expect to have rain or even a storm. If the pointer moves slowly downwards, light rain is very likely.