‘INSTRUMENTS AND TECHNIQUES FOR METEOROLOGICAL MEASUREMENTS 1221 
sensitivity and ruggedness of the infrared detectors and 
in part to the lack of precise water-vapor absorption 
coefficients for low temperatures and humidity. How- 
ever, this former difficulty should be somewhat eased 
with the use of the newer photoconductive cell and 
especially the nonselective pneumatic cell. Both of 
these detectors can readily be incorporated into stable 
electronic amplifiers and should result in a quite sensi- 
tive and accurate hygrometer. 
The possibility of probing the troposphere and middle 
stratosphere without the use of expendables is taking 
an encouraging turn, particularly through the use of 
radar techniques. Experimental equipments have been 
devised to probe cloud structures and locate the zero 
degree isotherm within the clouds whenever present. 
The location of precipitation areas through radar is 
also well known, and there are data on hand to suggest 
that some temperature inversions can be detected 
through the use of radar. For example, the work of 
Friend [14], using radar of frequencies ranging from 
100 to 10,000 me sec, points to the real possibility of 
discerning air-mass boundaries, surfaces of water-vapor 
transitions, and other fine structures associated with 
dielectric changes of the atmosphere, such as turbulence. 
Furthermore, Jones [17] has made a most interesting 
suggestion of utilizimg pulsed-lhght techniques for de- 
ducing the density field as a function of height. 
Recent advances in the art of balloon fabrication 
and in techniques of radio direction finding will prac- 
tically insure measurements of winds to about 35 km. 
Studies of the motion of noctilucent clouds in northern 
latitudes has given some information on wind velocities 
from 70 to 90 km. In addition the possibility of esti- 
mating winds in the vicinity of 160 km through doppler 
studies of meteor trails has been reported by Manning 
and Villard [23]. Recently, Crary [8] outlmed a method 
of obtaining wind estimates from 30 to 60 km by the 
study of the anomalous propagation of sound. However, 
in spite of these most interesting techniques, a real 
need exists for a method of measuring winds on a 
semiroutine basis at the critical altitudes of 35 to 80 — 
km. The use of smoke trails from V-2 rockets has not 
been successful at these very high altitudes. 
In an earlier section of this article it was stated that 
the white thermistor element could measure tempera- 
tures with an accuracy of +0.5C. Two of the important 
corrections that must be applied are those of lag and 
radiation, these errors becoming increasingly important 
at very high altitudes. According to Barrett and Suomi 
[8], one method of suppressing these sources of errors 
is to use a sonic thermometer. These investigators have 
described a very clever sonic thermometer based on a 
pulse feed-back principle and have claimed such im- 
provements as absence of radiation error and freedom 
from lag errors. In addition to.these advantages, it is 
emphasized that a sonic thermometer permits space 
integration of air temperatures as a means for obtain- 
ing air temperatures more representative than is pos- 
sible with pomt measurements. The question of space 
integration versus point measurements of temperature 
and winds is in need of clarification. 
The time has perhaps arrived to give serious consider- 
ation to the important problem of data-presentation 
schemes. The amount of raw data presented to the 
forecaster for analysis and study is truly staggering. 
He may now have available to him for consideration, 
in addition to standard surface observations, complete 
radiosonde and radiowind data to 100,000 ft, detailed 
data on bases and tops of clouds from various strategic 
observation stations, sferics data from a world-wide 
network, detailed radar storm information, and other 
miscellaneous data. From these raw data he may draw 
a multitude of thermodynamic diagrams and charts, 
wind trajectories, velocity fields, acceleration fields, 
etc., for a variety of pressure levels, for an entire 
hemisphere, and for several time intervals. Presumably 
the forecaster would want a three-dimensional presen- 
tation of the current state of the atmosphere and of 
significant variations therein. There appears to be gen- 
eral agreement that atmospheric changes are sufficiently 
complex that a simple representation of them is not 
feasible at best. 
It is suggested, therefore, that a careful over-all 
study of systems be undertaken at the earliest possible 
moment. Such a study would include an analysis of 
methods of obtaining raw data, of systems for data 
transmission, of possible utilization of analogue and 
digital computers, and finally a recommendation of an 
integrated data-presentation scheme. In the opinion of 
this writer such a cooperative study between system 
engineers and meteorologists is necessary to insure 
continuing progress in forecasting techniques. 
It is a pleasure to acknowledge the many valuable 
criticisms and suggestions given to the author by his 
colleagues in the Meteorological Branch of the Evans 
Signal Laboratory. 
REFERENCES 
1. AnpErson, L. J., ‘“‘Captive-Balloon Equipment for Low- 
Level Meteorological Soundings.’’ Bull. Amer. meteor. 
Soc., 28: 356-362 (1947). 
2. AnpErRson, P. A., and others, The Captive Radiosonde and 
Wiresonde Technique. N.D.R.C. Project P.D.R.C. 647, 
Report No. 3. 
3. Barrett, H. W., and Suomr, V. E., ‘‘Preliminary Report 
on Temperature Measurement by Sonic Means.” J. 
Meteor., 6: 273-276 (1949). 
4, Barrer, E. W., Hernpvon, L. R., Jr., and Carter, H. J., 
“A Preliminary Note on the Measurement of Water- 
Vapor Content in the Middle Stratosphere.” J. Meteor., 
6: 367-368 (1949). 
5. Bratusrorp, H. D., ‘““A New Code Transmitting Radio- 
sonde.’’ J. Meteor., 6: 360-362 (1949). 
6. Braserietp, C. J., “Measurement of Air Temperature in 
the Presence of Solar Radiation.” J. Meteor., 5: 147-151 
(1948). 
7. Carson, E., ‘‘Automatie Weather 
Weather Maps, Wash., July 27, 1948. 
8. Crary, A. P., ‘Stratosphere Winds and Temperatures from 
Acoustical Propagation Studies.” J. Meteor., 7: 283-242 
(1950). 
9. Dramonp, H., and Hinman, W. &., Jr., “An Automatic 
Weather Station.” (Research Paper 1318) J. Res. nat. 
Bur. Stand., 25: 188-148 (1940). 
Stations.”” Daily 
