pressure altimeter
Quick Summary
A pressure altimeter is an instrument used to measure altitude by determining atmospheric pressure. It operates on the principle that atmospheric pressure decreases linearly with altitude. The device typically uses an aneroid capsule, a thin, flexible, evacuated metal bellows, which expands or contracts with changes in external air pressure. This movement is mechanically translated to pointers on a dial, calibrated in feet or meters, to indicate altitude above sea level. Pressure altimeters must be adjusted to account for variations in atmospheric pressure due to weather conditions.123
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