One atmosphere is equal to 29.9 inches (760 mm) of mercury, or 760 mm H; atmospheres are the units of pressure used in the international standard, or SI, system of measurement. 1) How A Mercury Barometer Works.

The plastic and the taped section of straw sink, causing the end of the straw to tilt up. Mercury: • Can break into droplets when spilled. Follow these links for information on The first barometers used mercury as the liquid to show changes in air pressure. Glue or tape the narrow end to the container so that the wider end sits just behind the straw. The aneroid barometer has an airtight metal box inside, and once air pressure rises or falls, this box squashes inward or flexes outward a bit. The volume of the spill tray should be at least 110% that of the mercury being used. 4 mm and 8 mm are recommended. Trustworthy 500 expert co-authors across 30,000 articles. The plastic wrap bulges out, raising the taped end of the straw. Some of the mercury flows from the tube into the reservoir, creating a vacuum at the top of the closed end of the tube. It should be made from a smooth-surfaced plastic tray, not metal. Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. EPA cleaning up a mercury spill at a house. It is advisable to wear latex or nitrile close-fitting gloves. To use a Fortin barometer, the level of mercury is set to zero by using the thumbscrew to make an ivory pointer (O in the diagram) just touch the surface of the mercury.

Mercury is an amazing liquid - it is actually a metal which exists in liquid form at normal temperatures, and is about 13.5 times heavier than water.

4 mm and 8 mm are recommended.It is much easier for the students to see the mercury if the tube is placed in front of an illuminated sheet of translucent material. A suitable screen can be made of tracing paper in a wooden frame. Rising pressure is associated with dry, cool, and calm weather.

Even as late as the 1990s, National Weather Service offices still calibrated and verified the accuracy of the aneroid barometer with the mercurial barometer.

There are many units used to measure pressure; for years, millimeters of mercury, or mm Hg, was the unit of choice. You can make your own barometer using everyday materials and then try to forecast the weather yourself. The air trapped inside the mug is at atmospheric pressure and this keeps the water...The hot water heats up the air inside the glasses, which expands and some escapes. A lamp behind the tube ensures that the tube is seen in silhouette.Filling a barometer tube takes practice and needs a steady hand but it is well worth trying to master the art.It is very easy to take the atmosphere for granted and so it is important that...Pull the glass out and the tissue is…Dry! And like all homemade barometers it will work best if you make your barometer on a day which is neither too wet and stormy (low pressure) or sunny and still (high pressure).If you pick a day when the air pressure is at about the middle of its range, then the straw will have room to moveup or down as the air pressure changes.That's the end of the section on home experiments withair pressure and homemade barometers. And while most scientific attention was concentrated on the You may be interested to know that you can find out more about weather and home weather stations by receiving our newsletter ,If this sounds interesting, just add your name and email address to the form below. Another common variety of barometer is a mercury barometer.