Barometers
Barometers
Barometers are instruments that measure the pressure of air in a specific environment; barometer measurements are used to forecast weather and measure altitude.
Atmospheric pressure also depends on the planet’s mass, its surface radius, the gas concentrations and composition, and the gases’ vertical distribution in the atmosphere. It is also affected by the planet’s rotation and other local conditions including wind velocity and temperature-dependent density and gas composition variations.
Common pressure units include:
- Pounds per square inch (psi)
- Dynes per square centimeter
- Newtons per square meter (equivalent to the pascal, the SI unit)
- Inches, centimeters, or millimeters of mercury
- Millibars (1 millibar equals 1,000 dynes per square centimeter, 100 pascals, or 0.75 millimeters of mercury)
The pascal (Pa) or kilopascal (kPa) has worldwide use as a unit of pressure and has mostly replaced the unit of pounds per square inch. Exceptions are countries that use the imperial measurement system or the U.S. customary system.
In general, better or drier weather is indicated by a rising barometer; a falling barometer indicates worse or wetter weather.
Several types of quantitative or semi-quantitative barometers exist. Torricellian or mercury barometers use a column of mercury to balance atmospheric pressure. The height of the mercury is pre-measured, and the change in height is used to calculate the atmospheric pressure.
Nonliquid or aneroid (dial) barometers are used in portable instruments and aircraft altimeters because their smaller size offers convenience. A flexible-walled evacuated capsule moves with changes in atmospheric pressure – the movement mechanically moves an indicating needle. Recording aneroid barometers are called barographs.
Digital barometers contain a pressure transducer that converts the air pressure into an electrical signal.
Fisherbrand™ Traceable™ Digital Barometer
Perfect unit for plants and labs to monitor barometric pressure, temperature, relative humidity, barometric pressure trend and time-of-day. Fisherbrand Traceable Digital Barometer is ideal for use in environments where there is a need to monitor conditions of environmental air parameters.
Fisherbrand™ Traceable™ Precision Dial Barometers
Ideal for monitoring weather changes or environmental conditions in labs or plants
Fisherbrand™ Traceable™ Handheld Digital Barometer
Keep track of your environment and your time with this multi-functional Traceable™ Handheld Digital Barometer.
H-B Instrument™ Durac™ Barometer
Recalibrateable unit
TFA Dostmann Analog Mini Weather Station
The analog mini weather station, with a metallic finish plastic housing, is guaranteed to fit on any desk or shelf and it provides you with the latest data on temperature, air pressure,and humidity. The instrument is entirely manufactured in Germany. A compact instrument packed with information.
Digi-Sense™ Precalibrated Humidity and Temperature Indicators
Designed to gauge proper humidity levels
TFA Dostmann Wireless Weather Station ZENO
The wireless weather station ZENO has large digital display. The radio-controlled clock always shows the exact time and ensures punctuality, even when waking up. The inside and outside temperature is displayed, as well as the minimum and maximum values.
Fisherbrand™ Traceable™ Workstation Barometer with Clock
Ideal for recording ambient changes in the lab, monitoring conditions affecting sample analysis and assisting in the prediction of weather changes