Why Buy a Barometer

Even in these modern times of satellite phones and Internet, the atmospheric pressure measured with a personal barometer remains the most important indication of weather changes at your location. To evaluate present weather or to forecast coming weather, we need accurate barometric pressure. Most common barometers on the market are not accurate enough to serve this purpose. They are more decorative than functional.

Barometer vs. barograph?
A barometer displays the present pressure and the change of pressure since it was last set using a marker hand on the dial. A barograph records the history of the pressure on a paper chart, wrapped around a clock-driven drum. Underway on a fully crewed vessel, the logbook serves as a detailed record of pressure changes. On overnight anchorages, a printed barograph trace is a convenient way to learn how the pressure changed during the night when there was no watch to record it. Keep in mind, however, that with a good aneroid device you still have the set hand to learn how the pressure changed overnight. So if this is a concern, set the hand in the evening to the pressure then, and read the change in the morning.

Mechanical vs. electronic instruments?
Mechanical (aneroid) barometers have been used on land and sea continuously since the mid 1800s. By the 1960s, precision aneroid barometers were fully developed and available from selected dealers. Navies and weather-service vessels worldwide rely on these aneroid instruments daily. The Fischer precision aneroids are the last of original technology that revolutionized the aneroid technology in the 1950s. They are still produced today as they were 60 years ago, and they remain unmatched in dependability.

Electronic barometers are small pressure sensors, read and controlled by microprocessors with a digital and sometimes graphic display. They have been used in science laboratories for many years. Affordable models intended for public use have become popular in the past few years.

As with aneroid barometers, there is a wide range of quality in electronic barometers. All barometers should be periodically compared with known pressures from official weather services (see, for example, www.starpath.com/barometers). Also keep in mind, that many modern smart phones include a barometer sensor. Often they are not accessible without a third party app that reads and displays the pressure, but there are many free apps that do this. Preliminary tests show these as dependable over broad pressure ranges, though like all barometers, they need to be checked periodically for drift or offset.

Mariners have historically cared only about pressure trends (up or down, fast or slow). These are important observations (if made accurately), but the actual values of the pressure can be even more important in many modern applications. Specific pressure values are the best way to monitor the timing of a forecasted weather system, as well as to evaluate the forecast in general by checking mapped pressures with what you actually observed at the time of the map. Target pressures are the key to tactical weather routing, and this can only be done with accurate pressure observations.

A good barometer is much like a sextant for an ocean-going vessel. It is a one time investment in an instrument that will contribute to your safe navigation for a lifetime.

To learn how barometric pressure can be used in weather analysis see The Barometer Handbook.

We have a list of barometer related articles at the bottom of this page References and Resources for Barometer Use in Marine Navigation