TEMPERATURES AND PRESSURES IN THE UPPER ATMOSPHERE 
urements appear to hold the greatest promise for de- 
termining conditions in the upper atmosphere. Recent 
improvements in technique and the lessons of past 
experience indicate that good results should be forth- 
coming in the next few years. With the mobility afforded 
by the Navy’s Norton Sound, the measurements now 
being made at White Sands can be extended to widely 
separated parts of the world. The three branches of the 
Armed Forces are devoting considerable attention to 
this phase of rocket research in the upper atmosphere. 
Their efforts should aid materially in solving the tem- 
perature-pressure problem, at least for altitudes below 
150 km. A critically comparative survey of the field is 
probably best left in abeyance until more work has 
been done both with rockets and with other methods. 
A summary of current knowledge about atmospheric 
temperatures may be found from the N.A.C.A. Tenta- 
tive Standard Atmosphere, drawn up in 1947. This 
curve was shown in Fig. 4 for comparison with Cox’s 
sound propagation results. At the time it was con- 
structed, the tentative standard was intended to be a 
rough average of data then available. The wide varia- 
tion in temperature data was reflected in the upper and 
lower limits provided with the standard curve. Rocket 
results and Cox’s sound propagation measurements, 
obtained since issuance of the standard, indicate that 
the temperatures should be lowered in the neighborhood 
of 55 km to less than 300K. The rocket measurements 
also reveal quite low temperatures near 80 km, perhaps 
as low as 180K. This is in keeping with temperatures 
required for formation of noctilucent clouds seen near 
80 km in the higher latitudes. At present, however, the 
quantity of rocket data is too small, and the question 
of temporal, solar, and geographic influences too un- 
settled, to warrant changing the standard curve now. 
Hvidences of high temperatures, on the order of 
1000K or more, at several hundred kilometers and 
above, were presented in the preceding section. 
The best curves of pressure variation with altitude 
are probably those of Figs. 6 and 7, obtained from 
rocket soundings. ~- 
The rough sketch in the preceding paragraphs over- 
simplifies the true picture, as plainly it must, consider- 
ing the large number of variables involved. None of the 
measurements to date are adequate to pin down small 
local phenomena which may exist. Mother-of-pearl 
clouds, for example, appearing at 22 to 30 km, indicate 
a region of cooling at the top of the stratosphere. It is 
not unlikely that such local temperature variations 
come and go with time. The double hump shown in the 
Viking temperature curve of Fig. 8 appears real. Hints 
of such a phenomenon were seen in the reduction of 
other rocket data. As pointed out above, the presence of 
the two maxima suggests the possibility of two types of 
atmospheric heating. Possibly the lower altitude maxi- 
mum was due to ozone heating primarily, and the upper 
one to oxygen absorption of ultraviolet radiation below 
2000 A. Then again, the phenomenon may be due 
simply to mass motions in the air. Certainly wind 
structure and temperature of the atmosphere are closely 
associated. In particular, the effect of mixing or lack of 
309 
mixing upon composition of the air should influence 
atmospheric temperature-pressure relationships appre- 
ciably, although at present it appears that mixing below 
80 km is adequate to prevent any significant diffusive 
separation of atmospheric constituents. Heating in the 
E-layer of the ionosphere may be caused by an influx 
of X-radiation from the sun. 
Even a brief consideration of the complexity of the 
atmosphere serves to emphasize the need for an abun- 
dance of accurate data before a truly complete under- 
standing of the atmosphere can be had. Specifically: 
1.) Further flights with balloons to maximum attain- 
able altitudes are highly desirable. Such flights 
should be made over as wide a range of time and 
geographical position as is possible. 
2.) Extensive sound propagation studies in various 
parts of the world, with especial care to eliminate 
errors due to winds, should be made to obtain 
further temperature data. 
3.) Rocket pressure-temperature measurements 
should be extended to reach different latitudes 
and to cover the various times of day and year. 
Whenever possible, the experiments listed above 
should be conducted at the same time and place, 
and the results from the three methods carefully 
compared. 
5.) Absorption of terrestrial and solar radiations at 
the various altitudes should be measured in rocket 
flights to provide a basis for calculations of at- 
mospheric heating. These measurements also 
should cover a wide temporal and geographical 
range. 
6.) Rocket and balloon measurements of wind struc- 
ture in the upper atmosphere are essential. 
7.) Before the pressure-temperature problem in the 
upper atmosphere can be completely solved, at- 
mospheric composition at the various altitudes 
must be determined. It is to be hoped that rocket 
soundings can aid in this. 
8.) Eventually a careful, critical comparison of the 
various methods of determining atmospheric pres- 
sures, temperatures, and densities should be made 
to point up systematic differences, and to “‘cali- 
brate” the different methods, so to speak. With 
the Norton Sound the Armed Forces may be able 
within the next several years to provide enough 
rocket data to form a standard for comparison. 
Needless to say, not only the methods discussed 
above, but also others, such as ionospheric and 
spectroscopic studies, should be included in the 
comparison. 
4.) 
REFERENCES 
1. Best, N. R., Duranp, E., Gaus, D. I., and Havens, R. 
J., “Pressure and Temperature Measurements in the 
Upper Atmosphere.” Phys. Rev., 70: 985 (1946). 
2. Bust, N. R., Havens, R., and LaGow, H., ‘‘Pressure and 
Temperature of the Atmosphere to 120 km.” Phys. Rev., 
71: 915-916 (1947). 
3. Borne, G. v. v., “Uber die Schallverbreitung bei Explo- 
sionskatastrophen.”’ Phys. Z., 11: 483-488 (1910). 
