How to Compare Calibrations of Barometer Readings
A barometer is an instrument used to measure air pressure at a location. Barometers are used to predict the weather and are important for nautical and air navigation. Barometers measure the air pressure with respect to a certain elevation above sea level. The instrument should be calibrated by a professional. Calibration usually takes place in a vacuum chamber. After proper calibration, the readings are compared using a barometer-calibration table. The difference in the correction values gives an idea of how accurate or out of calibration the barometers are. Does this Spark an idea?
Instructions
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Set up the barometers on a stable, flat surface. Take note of the pressure reading on each of them. For example, one barometer might read 900 and the other might read 920.
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Consult the calibration table for the correction number associated with the reading. The correction number corresponds to the equation: Station Pressure = Barometer Reading +/- Calibration Correction. For the 900 barometer reading, look up 900 on the table and then look to the correction column. Do the same for the 920 reading. Input the results into the formula. If the 900 reading's correction factor is +0.2, then the pressure at the station equals 900.2 mb.
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Record the difference between calibration-correction numbers. These numbers are directly associated with the calibration of each specific barometer. The 900 reading's factor equaled +0.2 and the 920 reading's factor might be equal to +0.4. This shows that the barometer reading 920 required a larger correction factor compared with the one that read 900.
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Tips & Warnings
Graphing the information on the table on an x-y axis provides the difference in the slope between the calibration readings. A steeper slope means that more correction was required for a given barometer.
References
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