What does a mercurial barometer measure?

What does a mercurial barometer measure?

Based on a principle developed by Evangelista Torricelli in 1643, the Mercurial Barometer is an instrument used for measuring the change in atmospheric pressure. It uses a long glass tube, open at one end and closed at the other. Air pressure is measured by observing the height of the column of mercury in the tube.

What does a mercury barometer look like?

The classic mercury barometer is designed as a glass tube about 3 feet high with one end open and the other end sealed. The tube is filled with mercury. This glass tube sits upside down in a container, called the reservoir, which also contains mercury.

What are the different types of barometers?

There are two main types of barometers: mercury and aneroid.

How accurate is a mercury barometer?

The accuracy of these barometers can be as high as 0.008% of reading. Typically, a precision digital barometer used in calibrating other, lower accuracy barometers should be at least four times more accurate than the device being tested in order to maintain a 4:1 TUR (total uncertainty ratio).

What is the standard pressure for a mercury barometer?

14.70 pounds per square inch
Standard sea-level pressure, by definition, equals 760 mm (29.92 inches) of mercury, 14.70 pounds per square inch, 1,013.25 × 103 dynes per square centimetre, 1,013.25 millibars, one standard atmosphere, or 101.325 kilopascals.

Can I buy mercury for my barometer?

Old, contaminated mercury that may have been in the barometers is collected and recycled through a mercury processing company. No mercury is lost or discarded from my shop. There is no federal government restriction on buying mercury.

How do you read a barometer?

A barometer that has a high reading — meaning high pressure — and is stable, indicates good weather. You’re in the midst of a high pressure system. A barometer that is falling indicates that a low pressure system is moving in, and you can expect poorer weather.

Why are there two needles on a barometer?

In an aneroid barometer there are normally two needles. One is the measuring hand and the other is a movable pointer which you can adjust by turning the knob on the front. You should put your pointer needle directly over the measuring hand to set the barometer.

Is it OK to tap a barometer?

Any dial barometer aneroid or mercury will always have some amount of ‘sticktion’ therefore a GENTLE tap is normal. (Tapping actually helps the user as it indicates which way the barometer is moving at the time it is being looked at.)

Can old barometers be repaired?

Digital barometers are only meant to last eight years. In that time you may need to replace batteries and toward the end the liquid crystals will decay and the display will fade. Replacement of the crystals is the only means of repair.

What do the two hands on a barometer mean?

On an aneroid barometer, you’ll have two hands. One will show the barometric pressure reading, and the other is a manual dial that you align to the pressure reading whenever you take a measurement.

What is a normal barometer reading?

Know what represents reasonable barometer readings Normal is 29.9; range ~29.6 – 30.2 inches Hg (752-767 mm Hg)… at SEA LEVEL! Rarely (at sea level) do readings exceed 30.4 inches Hg (773 mm Hg)… except for occasional arctic highs in January.