Altitude
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- For other uses see Altitude (disambiguation)
Atmospheric pressure decreases with altitude. This principle is the basis of operation of the pressure altimeter, which is an aneroid barometer calibrated to indicate altitude instead of pressure.
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Altitude in aviation
In aviation, the term altitude can have several meanings. It is a fundamental tenet of flight safety that both parties exchanging information concerning this topic are absolutely clear which definition is being used. (AFM 51-40)
- True altitude is the elevation above mean sea level. In UK aviation radiotelephony usage, the vertical distance of a level, a point or an object considered as a point, measured from mean sea level; below the Transition Level this is referred to over the radio as altitude. (CAP413)
- Absolute altitude or height is the elevation above a ground reference point, commonly the terrain elevation. In UK aviation radiotelephony usage, the vertical distance of a level, a point or an object considered as a point, measured from a specified datum; below the Transition Level this is referred to over the radio as height, where the specified datum is the airfield elevation. (CAP413)
- Indicated altitude is the reading on the altimeter when it is calibrated to the local barometric pressure, referred to as the "altimeter setting". (See also QNH and QFE).
- Pressure altitude is the elevation above a standard datum plane (typically, 1013.2 millibars). Above a transition altitude, which varies by nation, pressure altitude is used to set the altimeter. Pressure altitude divided by 100 is referred to as the flight level.
- Density altitude is the altitude in the International Standard Atmosphere (ISA) at which the air density is equal to local conditions. Aircraft performance depends on density altitude, which is affected by barometric pressure and temperature. On a very hot day, density altitude at an airport may be so high as to preclude takeoff, particularly for helicopters or a heavily loaded aircraft.
Altitude regions
Mountain medicine recognizes three altitude regions: (Non-Physician Altitude Tutorial)- High altitude = 1500 m – 3500 m
- Very High altitude = 3500 m – 5500 m
- Extreme altitude = 5500 m – above
- Troposphere — surface to 8 km (above poles) – 18 km (above equator), ending at the Tropopause.
- Stratosphere — Tropopause to 31 miles
- Mesosphere — Stratopause to 53 miles
- Thermosphere — Mesopause to 420 miles
- Exosphere — Thermopause to 6200 miles
Altitude records
- redirect [[Template:Not verified]]
- 19 September, 1783 — 500 m (1,700ft) animal carrying Montgolfier hot-air balloon.
- 15 October, 1783 — 26 m (84ft) Pilâtre de Rozier in a Montgolfier tethered balloon.
- 1 December, 1783 — 2.7 km Professor Charles and assistant Robert in Charliere, his hydrogen-filled balloon.
- 1784 — 4 km Pilâtre de Rozier and the chemist Proust in a Montgolfier.
- 18 July, 1803 — 7.28 km Etienne Gaspar Robertson and Lhoest in a balloon.
- 1839 — 7.9 km Charles Green and Spencer Rush in a free balloon.
- 5 September, 1862 — 9 km Coxwell and English physicist Glaisher in a balloon.
- 4 December, 1894 — 9.155 km German meteorologist Berson in an airship.
- 31 July, 1901 — 10.8 km German meteorologist Berson and Süring in a free balloon.
References
External links
- [Downloadable ETOPO2 Raw Data Database (2 minute grid)]
- [Downloadable ETOPO5 Raw Data Database (5 minute grid)]
See also
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