280 



Table 68 



NACA STANDARD ATMOSPHERE, TENTATIVE PROPERTIES OF THE 

 UPPER ATMOSPHERE i* 



Recent developments in aeronautics and ordnance have demonstrated the need for 

 information concerning the characteristics of the upper atmosphere. As a result of this 

 need the National Advisory Committee for Aeronautics has prepared tentative tables of 

 pertinent properties of the atmosphere for altitudes extending to 120 kilometers. The 

 tables are intended to serve as a tentative standard for evaluating the performance 

 characteristics of aircraft, missiles, and prime movers, and for design purposes, and con- 

 stitute an extension of Table 63, "Standard Atmosphere, Lower Atmosphere." 



Tentative temperatures. — Three sets of tentative temperature-height relationships have 

 been adopted. One set gives tentative standard temperatures which are used as the 

 basis of the tables and the other two list values of the probable minimum and the prob- 

 able maximum temperatures for the entire world. These three sets of temperature dis- 

 tributions which were originally recommended by the NACA Subcommittee on the 

 Upper Atmosphere are given by linear variations with altitude between the points specified 

 in the following tabulation of temperatures : 



TEMPERATURES 



83 

 120 



170 

 300 



240 

 375 



300 



600 



Tentative composition. — The tentative composition used in computing the table was 

 arrived at by taking into consideration the fact that, at altitudes below 80 kilometers in 

 the daytime and below 105 kilometers at night, the generally accepted variations in 

 chemical composition are too small to affect appreciably the computed pressures and 

 densities. However, it is believed that at levels above those just specified significant 

 changes in composition result from the dissociation of oxygen molecules by solar radiation. 

 It is furthermore known that the presence of water vapor in the atmosphere does not 

 appreciably affect pressures and densities in the upper atmosphere. As a result of such 

 considerations, and in the interest of simplicity, the following tentative specifications for 



1 Condensed from Warfield, C. N., Tentative tables for the properties of the upper atmosphere, 

 NACA Techn. Note No. 1200, 1947. 



2 The values of ambient air temperature listed in these two columns are not intended to represent 

 extreme values for the entire world, and for all time, but rather values that bracket the temperatures 

 over nearly all the earth most of the time. It is, of course, unlikely that at any given time the 

 atmosphere will assume the "probable minimum" (or "maximum") temperature distribution throughout 

 its depth or through any major segment thereof. 



* Superseded by U. S. Extension to ICAO Standard Atmosphere, 1956. Geophysics Research Direc- 

 torate, Air Force Cambridge Research Center, and U. S. Weather Bureau. 



(continued) 



SMITHSONIAN METEOROLOGICAL TABLES 



