Difference between revisions of "Standard atmosphere"

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#<div class="definition"><div class="short_definition">A hypothetical vertical distribution of atmospheric [[temperature]], [[pressure]],  and [[density]] that, by international agreement, is taken to be representative of the [[atmosphere]]  for purposes of [[pressure altimeter]] calibrations, aircraft performance calculations, aircraft and  missile design, ballistic tables, etc.</div><br/> <div class="paragraph">The air is assumed to obey the [[perfect gas]] law and the [[hydrostatic equation]], which, taken  together, relate temperature, pressure, and density variations in the vertical. It is further assumed  that the air contains no [[water vapor]] and that the acceleration of [[gravity]] does not change with  height. This last assumption is tantamount to adopting a particular unit of [[geopotential height]]  in place of a unit of geometric height for representing the measure of vertical displacement, for  the two units are numerically equivalent in both the metric and English systems, as defined in  connection with the standard atmosphere. The current standard atmosphere is that adopted in  1976 and is a slight modification of one adopted in 1952 by the International Civil Aeronautical  Organization (ICAO), which, in turn, supplanted the NACA Standard Atmosphere (or U.S. Standard  Atmosphere) prepared in 1925. It assumes [[sea level]] values as follows:   
 
#<div class="definition"><div class="short_definition">A hypothetical vertical distribution of atmospheric [[temperature]], [[pressure]],  and [[density]] that, by international agreement, is taken to be representative of the [[atmosphere]]  for purposes of [[pressure altimeter]] calibrations, aircraft performance calculations, aircraft and  missile design, ballistic tables, etc.</div><br/> <div class="paragraph">The air is assumed to obey the [[perfect gas]] law and the [[hydrostatic equation]], which, taken  together, relate temperature, pressure, and density variations in the vertical. It is further assumed  that the air contains no [[water vapor]] and that the acceleration of [[gravity]] does not change with  height. This last assumption is tantamount to adopting a particular unit of [[geopotential height]]  in place of a unit of geometric height for representing the measure of vertical displacement, for  the two units are numerically equivalent in both the metric and English systems, as defined in  connection with the standard atmosphere. The current standard atmosphere is that adopted in  1976 and is a slight modification of one adopted in 1952 by the International Civil Aeronautical  Organization (ICAO), which, in turn, supplanted the NACA Standard Atmosphere (or U.S. Standard  Atmosphere) prepared in 1925. It assumes [[sea level]] values as follows:   
#:<div class="list_item">&mdash;Temperature 288.15 K (15&deg;C)</div>  
+
#:<div class="list_item">&mdash;Temperature 288.15 K (15&#x000b0;C)</div>  
 
#:<div class="list_item">&mdash;Pressure 101 325 Pa (1013.25 mb, 760 mm of Hg, or 29.92 in. of Hg)</div>  
 
#:<div class="list_item">&mdash;Pressure 101 325 Pa (1013.25 mb, 760 mm of Hg, or 29.92 in. of Hg)</div>  
#:<div class="list_item">&mdash;Density 1225 g m<sup>&minus;2</sup> (1.225 g L<sup>&minus;1</sup>)</div>  
+
#:<div class="list_item">&mdash;Density 1225 g m<sup>-2</sup> (1.225 g L<sup>-1</sup>)</div>  
#:<div class="list_item">&mdash;Mean molar mass &mdash; 28.964 g [[mole]]<sup>&minus;1</sup>.</div><br/> The parametric assumptions and physical constants used in preparing the current standard atmosphere  are as follows.
+
#:<div class="list_item">&mdash;Mean molar mass &mdash; 28.964 g [[mole]]<sup>-1</sup>.</div><br/> The parametric assumptions and physical constants used in preparing the current standard atmosphere  are as follows.
##<div class="list_item">Zero [[pressure altitude]] corresponds to that pressure that will support a column of [[mercury]]  760 mm high. This pressure is taken to be 1.013250 &times; 10<sup>6</sup> dynes cm<sup>&minus;2</sup>, or 1013.250 mb, and is  known as one standard atmosphere or one atmosphere.</div>
+
##<div class="list_item">Zero [[pressure altitude]] corresponds to that pressure that will support a column of [[mercury]]  760 mm high. This pressure is taken to be 1.013250 &times; 10<sup>6</sup> dynes cm<sup>-2</sup>, or 1013.250 mb, and is  known as one standard atmosphere or one atmosphere.</div>
##<div class="list_item">The [[gas constant]] for [[dry air]] is 2.8704 &times; 10<sup>6</sup> ergs gm<sup>&minus;1</sup>K<sup>&minus;1</sup>.</div>
+
##<div class="list_item">The [[gas constant]] for [[dry air]] is 2.8704 &times; 10<sup>6</sup> ergs gm<sup>-1</sup>K<sup>-1</sup>.</div>
 
##<div class="list_item">The [[ice point]] at one standard atmosphere pressure is 273.16 K.</div>
 
##<div class="list_item">The [[ice point]] at one standard atmosphere pressure is 273.16 K.</div>
##<div class="list_item">The [[acceleration of gravity]] is 980.665 cm s<sup>&minus;2</sup>.</div>
+
##<div class="list_item">The [[acceleration of gravity]] is 980.665 cm s<sup>-2</sup>.</div>
##<div class="list_item">The temperature at zero pressure altitude is 15&deg;C or 288.15 K.</div>
+
##<div class="list_item">The temperature at zero pressure altitude is 15&#x000b0;C or 288.15 K.</div>
##<div class="list_item">The density at zero pressure altitude is 0.0012250 gm cm<sup>&minus;3</sup></div>
+
##<div class="list_item">The density at zero pressure altitude is 0.0012250 gm cm<sup>-3</sup></div>
##<div class="list_item">The [[lapse rate]] of temperature in the [[tropopause]] is 6.5&deg;C km<sup>&minus;1</sup>.</div>
+
##<div class="list_item">The [[lapse rate]] of temperature in the [[tropopause]] is 6.5&#x000b0;C km<sup>-1</sup>.</div>
 
##<div class="list_item">The pressure altitude of the tropopause is 11 km.</div>
 
##<div class="list_item">The pressure altitude of the tropopause is 11 km.</div>
##<div class="list_item">The temperature at the tropopause is &minus;56.5&deg;C.</div><br/>The [[ARDC Model Atmosphere]], 1959, extended the above standard approximately as follows:
+
##<div class="list_item">The temperature at the tropopause is -56.5&#x000b0;C.</div><br/>The [[ARDC Model Atmosphere]], 1959, extended the above standard approximately as follows:
##<div class="list_item">The lapse rate from 11 to 25 km is 0&deg;C km<sup>&minus;1</sup>.</div>
+
##<div class="list_item">The lapse rate from 11 to 25 km is 0&#x000b0;C km<sup>-1</sup>.</div>
##<div class="list_item">The lapse rate from 25 to 47 km is +3.0&deg;C km<sup>&minus;1</sup>; temperature at 47 km is +9.5&deg;C.</div>
+
##<div class="list_item">The lapse rate from 25 to 47 km is +3.0&#x000b0;C km<sup>-1</sup>; temperature at 47 km is +9.5&#x000b0;C.</div>
##<div class="list_item">The lapse rate from 47 to 53 km is 0&deg;C km<sup>&minus;1</sup>.</div>
+
##<div class="list_item">The lapse rate from 47 to 53 km is 0&#x000b0;C km<sup>-1</sup>.</div>
##<div class="list_item">The lapse rate from 53 to 75 km is &minus;3.9&deg;C km<sup>&minus;1</sup>; temperature at 75 km is &minus;76.3&deg;C.</div>
+
##<div class="list_item">The lapse rate from 53 to 75 km is -3.9&#x000b0;C km<sup>-1</sup>; temperature at 75 km is -76.3&#x000b0;C.</div>
##<div class="list_item">The lapse rate from 75 to 90 km is 0&deg;C km<sup>&minus;1</sup>.</div>
+
##<div class="list_item">The lapse rate from 75 to 90 km is 0&#x000b0;C km<sup>-1</sup>.</div>
##<div class="list_item">The lapse rate from 90 to 126 km is +3.5&deg;C km<sup>&minus;1</sup>; temperature at 126 km is +49.7&deg;C  (molecular-scale temperatures).</div>
+
##<div class="list_item">The lapse rate from 90 to 126 km is +3.5&#x000b0;C km<sup>-1</sup>; temperature at 126 km is +49.7&#x000b0;C  (molecular-scale temperatures).</div>
##<div class="list_item">The lapse rate from 126 to 175 km is +10.0&deg;C km<sup>&minus;1</sup>; temperature at 175 km is 539.7&deg;C  (molecular-scale temperatures).</div>
+
##<div class="list_item">The lapse rate from 126 to 175 km is +10.0&#x000b0;C km<sup>-1</sup>; temperature at 175 km is 539.7&#x000b0;C  (molecular-scale temperatures).</div>
##<div class="list_item">The lapse rate from 175 to 500 km is +5.8&deg;C km<sup>&minus;1</sup>; temperature at 500 km is 2424.7&deg;C  (molecular-scale temperatures).</div><br/>The U.S. Extension to the ICAO Standard Atmosphere is essentially a recomputation of the above  data from the surface to 300 km. <br/>''See'' [[air]].</div><br/> </div>
+
##<div class="list_item">The lapse rate from 175 to 500 km is +5.8&#x000b0;C km<sup>-1</sup>; temperature at 500 km is 2424.7&#x000b0;C  (molecular-scale temperatures).</div><br/>The U.S. Extension to the ICAO Standard Atmosphere is essentially a recomputation of the above  data from the surface to 300 km. <br/>''See'' [[air]].</div><br/> </div>
#<div class="definition"><div class="short_definition">A standard unit of [[atmospheric pressure]], the 45&deg; [[atmosphere]], defined as that [[pressure]]  exerted by a 760-mm column of [[mercury]] at 45&deg; latitude at [[sea level]] at [[temperature]] 0&deg;C ([[acceleration  of gravity]] = 980.616 cm s<sup>&minus;2</sup>).</div><br/> <div class="paragraph">One 45&deg; atmosphere = 760 mm Hg (45&deg;) = 29.9213 in Hg (45&deg;) = 1013.200 mb = 101.320  kPa.</div><br/> </div>
+
#<div class="definition"><div class="short_definition">A standard unit of [[atmospheric pressure]], the 45&#x000b0; [[atmosphere]], defined as that [[pressure]]  exerted by a 760-mm column of [[mercury]] at 45&#x000b0; latitude at [[sea level]] at [[temperature]] 0&#x000b0;C ([[acceleration of gravity|acceleration  of gravity]] = 980.616 cm s<sup>-2</sup>).</div><br/> <div class="paragraph">One 45&#x000b0; atmosphere = 760 mm Hg (45&#x000b0;) = 29.9213 in Hg (45&#x000b0;) = 1013.200 mb = 101.320  kPa.</div><br/> </div>
#<div class="definition"><div class="short_definition">A standard unit of [[atmospheric pressure]], defined as that [[pressure]] exerted by a 760-mm  column of [[mercury]] at [[standard gravity]] (980.665 cm s<sup>&minus;2</sup> at [[temperature]] 0&deg;C).</div><br/> <div class="paragraph">This is a unit recommended for meteorological use. One standard atmosphere = 760 mm Hg =  29.9213 in Hg = 1013.250 mb = 101.325 kPa.</div><br/> </div>
+
#<div class="definition"><div class="short_definition">A standard unit of [[atmospheric pressure]], defined as that [[pressure]] exerted by a 760-mm  column of [[mercury]] at [[standard gravity]] (980.665 cm s<sup>-2</sup> at [[temperature]] 0&#x000b0;C).</div><br/> <div class="paragraph">This is a unit recommended for meteorological use. One standard atmosphere = 760 mm Hg =  29.9213 in Hg = 1013.250 mb = 101.325 kPa.</div><br/> </div>
#<div class="definition"><div class="short_definition">With respect to radio propagation, that hypothetical [[atmosphere]] in which [[standard propagation]]  exists, that is, one in which the [[index of refraction]] decreases with height at a rate of 12 [[N-  units]] per 1000 ft.</div><br/> </div><div class="reference">COESA 1976. U.S. Standard Atmosphere. U.S. Gov. Print. Off., Wash., D.C. </div><br/> <div class="reference">Jursa, A. S., ed. 1985. Handbook of Geophysics and the Space Environment. Air Force Geophysics Laboratory. </div><br/> <div class="reference">Minzner, R. A., K. S. W. Champion, and H. L. Pond 1959. The ARDC Model Atmosphere, 1959. Air Force  Surveys in Geophysics No. 115 (AFCRC-TR-59-267), Air Force Cambridge Research Center. </div><br/>  
+
#<div class="definition"><div class="short_definition">With respect to radio propagation, that hypothetical [[atmosphere]] in which [[standard propagation]]  exists, that is, one in which the [[index of refraction]] decreases with height at a rate of 12 [[N-unit|N-  units]] per 1000 ft.</div><br/> </div><div class="reference">COESA 1976. U.S. Standard Atmosphere. U.S. Gov. Print. Off., Wash., D.C. </div><br/> <div class="reference">Jursa, A. S., ed. 1985. Handbook of Geophysics and the Space Environment. Air Force Geophysics Laboratory. </div><br/> <div class="reference">Minzner, R. A., K. S. W. Champion, and H. L. Pond 1959. The ARDC Model Atmosphere, 1959. Air Force  Surveys in Geophysics No. 115 (AFCRC-TR-59-267), Air Force Cambridge Research Center. </div><br/>  
 
</div>
 
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Latest revision as of 17:58, 25 April 2012



standard atmosphere

  1. A hypothetical vertical distribution of atmospheric temperature, pressure, and density that, by international agreement, is taken to be representative of the atmosphere for purposes of pressure altimeter calibrations, aircraft performance calculations, aircraft and missile design, ballistic tables, etc.

    The air is assumed to obey the perfect gas law and the hydrostatic equation, which, taken together, relate temperature, pressure, and density variations in the vertical. It is further assumed that the air contains no water vapor and that the acceleration of gravity does not change with height. This last assumption is tantamount to adopting a particular unit of geopotential height in place of a unit of geometric height for representing the measure of vertical displacement, for the two units are numerically equivalent in both the metric and English systems, as defined in connection with the standard atmosphere. The current standard atmosphere is that adopted in 1976 and is a slight modification of one adopted in 1952 by the International Civil Aeronautical Organization (ICAO), which, in turn, supplanted the NACA Standard Atmosphere (or U.S. Standard Atmosphere) prepared in 1925. It assumes sea level values as follows:
    —Temperature 288.15 K (15°C)
    —Pressure 101 325 Pa (1013.25 mb, 760 mm of Hg, or 29.92 in. of Hg)
    —Density 1225 g m-2 (1.225 g L-1)
    —Mean molar mass — 28.964 g mole-1.

    The parametric assumptions and physical constants used in preparing the current standard atmosphere are as follows.
    1. Zero pressure altitude corresponds to that pressure that will support a column of mercury 760 mm high. This pressure is taken to be 1.013250 × 106 dynes cm-2, or 1013.250 mb, and is known as one standard atmosphere or one atmosphere.
    2. The gas constant for dry air is 2.8704 × 106 ergs gm-1K-1.
    3. The ice point at one standard atmosphere pressure is 273.16 K.
    4. The acceleration of gravity is 980.665 cm s-2.
    5. The temperature at zero pressure altitude is 15°C or 288.15 K.
    6. The density at zero pressure altitude is 0.0012250 gm cm-3
    7. The lapse rate of temperature in the tropopause is 6.5°C km-1.
    8. The pressure altitude of the tropopause is 11 km.
    9. The temperature at the tropopause is -56.5°C.

      The ARDC Model Atmosphere, 1959, extended the above standard approximately as follows:
    10. The lapse rate from 11 to 25 km is 0°C km-1.
    11. The lapse rate from 25 to 47 km is +3.0°C km-1; temperature at 47 km is +9.5°C.
    12. The lapse rate from 47 to 53 km is 0°C km-1.
    13. The lapse rate from 53 to 75 km is -3.9°C km-1; temperature at 75 km is -76.3°C.
    14. The lapse rate from 75 to 90 km is 0°C km-1.
    15. The lapse rate from 90 to 126 km is +3.5°C km-1; temperature at 126 km is +49.7°C (molecular-scale temperatures).
    16. The lapse rate from 126 to 175 km is +10.0°C km-1; temperature at 175 km is 539.7°C (molecular-scale temperatures).
    17. The lapse rate from 175 to 500 km is +5.8°C km-1; temperature at 500 km is 2424.7°C (molecular-scale temperatures).

      The U.S. Extension to the ICAO Standard Atmosphere is essentially a recomputation of the above data from the surface to 300 km.
      See air.

  • A standard unit of atmospheric pressure, the 45° atmosphere, defined as that pressure exerted by a 760-mm column of mercury at 45° latitude at sea level at temperature 0°C (acceleration of gravity = 980.616 cm s-2).

    One 45° atmosphere = 760 mm Hg (45°) = 29.9213 in Hg (45°) = 1013.200 mb = 101.320 kPa.

  • A standard unit of atmospheric pressure, defined as that pressure exerted by a 760-mm column of mercury at standard gravity (980.665 cm s-2 at temperature 0°C).

    This is a unit recommended for meteorological use. One standard atmosphere = 760 mm Hg = 29.9213 in Hg = 1013.250 mb = 101.325 kPa.

  • With respect to radio propagation, that hypothetical atmosphere in which standard propagation exists, that is, one in which the index of refraction decreases with height at a rate of 12 N- units per 1000 ft.

    COESA 1976. U.S. Standard Atmosphere. U.S. Gov. Print. Off., Wash., D.C.

    Jursa, A. S., ed. 1985. Handbook of Geophysics and the Space Environment. Air Force Geophysics Laboratory.

    Minzner, R. A., K. S. W. Champion, and H. L. Pond 1959. The ARDC Model Atmosphere, 1959. Air Force Surveys in Geophysics No. 115 (AFCRC-TR-59-267), Air Force Cambridge Research Center.