How Does a Barometer Work?

A barometer is an instrument that measures air pressure. It uses mercury, which reacts to air pressure just as it reacts to temperature in a thermometer, by rising or falling in a glass tube.

Perhaps you’re wondering why it is important to know something about air pressure. The answer is that it is an important aid to scientists who need to predict changes in the weather. A falling barometer, one in which the mercury falls quickly, is a sign of an approaching storm, while one in which the mercury is rising is an indication of good weather.

In a barometer, the mercury is sealed in a glass tube with a bulb at one end to serve as a reservoir, much like a thermometer. As air presses on the reservoir, the mercury is forced up into the tube. When the air pressure drops, so does the mercury.

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

3 thoughts on “How Does a Barometer Work?”

  1. Does a barometer work better on a specific wall. Inside, or outside?

    I bought a really nice one, but it never moves, can anyone help Thanks Sandy

  2. you sound like you might know how to work my barometer. It is on a inside wall, but never moves. Does it need to be on a outside wall. Can you help. A storm in due and I would like it to work for me. Help if you can Sandy

  3. I used this website’s article about barometers for my science fair project and it was excessively helpful!! I would recommend it to anyone who needs information for school/work! (Or if you’re just curious about something) this is a very cool site and it helped me with my school project.

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