An altimeter, or altitude meter, is an instrument used to measure the altitude of an object relative to a fixed level, with the underlying process called altimetry, related to the underwater equivalent called bathymetry. Pressure altimeters became the standard for aircraft, while skydivers and hikers adopted wrist mounted versions, and in 1931 the US Army Air Corps and General Electric together tested a sonic altimeter for aircraft that used high pitched sounds, similar to bat echolocation, to gauge distance from the surface. Modern altimeters now use several other technologies as well, including radar systems that measure how long a signal takes to reflect back, laser based lidar used on Mars rovers, and satellite navigation systems such as GPS that work out elevation by using signals from multiple satellites. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/
Facts
SignificanceThe pressure altimeter converts a barometer's air-pressure reading into an altitude reading, since atmospheric pressure falls in a known way as altitude rises. It has been the standard altitude instrument in aircraft cockpits, weather balloons, and mountaineering and skydiving equipment for more than two centuries. 1 Partially Attested
Patent or First-Use DateYear-only precision. The source names 1772 as the year Rev. Alexander Bryce first realised that barometric principles could be adapted to measure height; this is the earliest documented conceptual origin of the pressure altimeter, not a specific patent, and the source gives no exact day or month. Connections
Preceded By
Barometer, Inventions The pressure altimeter is a barometer recalibrated to read altitude instead of pressure.
Source Pressure Altimeter (Wikipedia)
Sources
1. Pressure Altimeter (Wikipedia)
Wikimedia FoundationHistory section
The scientific principles behind the pressure altimeter were first written by Rev. Alexander Bryce, a Scottish minister and astronomer who in 1772 realised that the principles of a barometer could be adjusted to measure height.
Lead section
Altitude can be determined by the measurement of atmospheric pressure. The greater the altitude, the lower the pressure. When a barometer is supplied with a nonlinear calibration so as to indicate altitude, the instrument is a type of altimeter called a pressure altimeter or barometric altimeter.
- In Group: Aircraft Flight Instruments, lead: altitude determined by measurement of atmospheric pressure via a nonlinear-calibrated barometer
View the Source Altimeter (Wikipedia)
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