The instrument, most commonly used in science, is a
The word, Barometer, is derived from baro, meaning weight
or pressure, and meter, meaning measuring device.
Barometers can be either analog or digital. The traditional
analog barometer is known as an aneroid barometer. These are
the round chrome or brass type that you would normally see on the
bridge of a ship, many times accompanied by clock, temperature,
and/or humidity gauge.
For an accurate and reliable aneroid barometer, you should
expect to pay $249.00 or more. For aneroid barometers, accuracy and
reliability will wane incrementally below that price. The cost of
scientific instruments, including barometers, are directly tied to
accuracy and reliability. In some cases, however, as you go up in
price, accuracy will remain stable but quality of materials and
craftsmanship will drive the price upwards (i.e. use of thick solid
brass or chrome).
Digital barometers emulate the results achieved from an aneroid
barometer (sometimes called a "nautical barometer). Their accuracy
varies wildly and is not necessarily tied to price. For
example, the barometers, in even the most reasonably priced (under
$100.00) La Crosse Weather Stations, are exemplary performers.
Anecdotal observations over many years show that the La Crosse
variance from NIST traceable, accurate weather stations has been
minimal (±.01). Other inexpensive manufacturer's products have
nowhere near this steady and predictable tolerance. And many are as
much as .06-.10 or 2-3mb off after initial calibration.
All barometers are not the same. Most have elevation
limitations. With the Weems & Plath barometers, specific
elevations are designated by each individual product. So, be sure
to probe for this information before you buy. Some barometers can
be upgraded for high elevation use. But this is relatively
expensive, and generally for those barometers to be used in terrain
Digital barometers can have the same limitations. Again, be
careful when you purchase. We are not aware of any low cost
digital that will function correctly over 5,000-6,000 ft elevation.
For high altitudes, or if you're a stickler for accuracy, you must
consider the Davis, RainWise, WeatherHawk, or Columbia Weather
Systems. Do not rely on any barometer above 5,000-6,000 ft for
mission critical or safety applications, unless you are absolutely
certain of its well defined and guaranteed specifications. Remember
that as you begin to challenge the stated limitations of any
scientific device, your inaccuracies will almost certainly increase
as you approach the stated threshold. For example, a stated 6,000
ft elevation limit may function perfectly well up to 4,000 ft.
Then, possibly a gradual fall-off in accuracy between
4,000-5,000ft. But then a rapid and possibly logarithmic increase
in error percentage over 5,000ft. This is just an example and not
meant to be a basis for calculating decreasing accuracy in any
The original analog barometer was the water ball. This
instrument featured a glass reservoir at its bottom that fed into a
narrowing tube that protruded upwards. As atmospheric pressure
increased, the water was driven upwards into the tube, to indicate
fair or improving weather conditions. Conversely, as the air
pressure dropped, the water level in the tube fell, to indicate a
change to more inclement weather. As the water level fell even
lower in the tube, it became a more urgent indicator of impending