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Welcome to the Dauntless Aviation Glossary!
At Dauntless, our editorial staff maintains the web's largest unified glossary of aviation terms. This glossary is built from a combination of official, quasi-official,
and proprietary sources (including original material that we develop oursselves). Uniquely, we often provide multiple definitions of a given term so that you can find that which best applies
to you. In order to maximize your learning efficiency, this glossary (and similar ones for our international users) is incresingly fully integrated into our aviation learning apps, including
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Standard Atmosphere (ISA)
| Standard Atmosphere (ISA) | | | The International Standard Atmosphere (ISA) is an atmospheric model of how the pressure, temperature, density, and viscosity of the Earth's atmosphere change over a wide range of altitudes or elevations. It has been established to provide a common reference for temperature and pressure and consists of tables of values at various altitudes, plus some formulas by which those values were derived. The International Organization for Standardization (ISO) publishes the ISA as an international standard, ISO 2533:1975. Other standards organizations, such as the International Civil Aviation Organization (ICAO) and the United States Government, publish extensions or subsets of the same atmospheric model under their own standards-making authority. The ISA model divides the atmosphere into layers with linear temperature distributions. The other values are computed from basic physical constants and relationships. Thus the standard consists of a table of values at various altitudes, plus some formulas by which those values were derived. For example, at sea level the standard gives - a pressure of 1013.25 hPa (1 atm) ( equivalent to 29.92 inches of mercury)
- a temperature of 15 degrees Celsius
- an initial lapse rate of ?6.5 °C/km (roughly ?2 °C/1,000 ft).
The tabulation continues to 11 km where the pressure has fallen to 226.32 hPa and the temperature to ?56.5 °C. Between 11 km and 20 km the temperature remains constant. | | source: Wikitionary / Wikipedia and Related Sources (Edited) |
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Disclaimer: While this glossary in most cases is likely to be highly accurate and useful, sometimes, for any number of editorial, transcription, technical, and other reasons, it might not be.
Additionally, as somtimes you may have found yourself brought to this page through an automated term matching system, you may find definitions here that do not match the cotext or application in which
you saw the original term. Please use your good judgement when using this resource.
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