726 
portant application of the isentropic chart proved to 
be its use in forecasting cloudiness and precipitation, 
including the evasive summertime showers. The chart 
was also found to be of especial value in predicting the 
occurrence of precipitation along the West Coast [6], 
where frontal analysis taken by itself is inadequate for 
this purpose. 
Unfortunately the years of experimentation drew to 
a close with only a small portion of the meteorologists 
in the United States familiar with the applications of 
the isentropic chart. Subsequently the isentropic chart 
was abandoned by the Weather Bureau and the data 
for its construction were no longer transmitted over the 
teletype network. This was due in part to certain 
difficulties in communication, but to a larger extent it 
was due to the time factor inherent in the analysis 
itself. The isentropic chart is more difficult to draw 
correctly than are most of our other upper-level charts. 
For inexperienced men the analytical time consumption 
proved to be an unsurmountable obstacle to the realiza- 
tion of the usefulness of the chart. Experienced fore- 
casters and analysts, however, who had become familiar 
with the isentropic chart generally felt, and still feel, 
that a long step backwards was taken when the isen- 
tropic analysis was abandoned. 
With the present trend towards the concentration of 
analysis in large centers, with the increased accuracy of 
radiosondes, and with the advent of improved com- 
munication facilities, the time seems ripe for the re- 
inauguration of the isentropic chart. It would be entirely 
possible for the analysis center to transmit to field 
forecast centers three complete isentropic charts, based 
on the same data that were previously transmitted from 
the observational network. With the advent of a means 
for transmitting colors, these isentropic charts could 
include not only streamlines, some sort of contour lines, 
and condensation height or pressure lines, but they 
could include, as well, moist tongues shaded in red, dry 
tongues in blue, and saturated areas in green in con- 
formance with the conventions observed previously in 
the construction of isentropic charts. Thus the forecaster 
would be provided with a simple efficacious tool for 
studying the moisture distribution of the atmosphere. 
Moreover, instead of having one “homemade” isen- 
tropic chart, plus the raw data for two other constant 
potential temperature surfaces, he would be equipped 
with carefully executed analyses for all three surfaces, 
enabling him to investigate the changes with respect to 
height of all the data on the isentropic chart. 
Such an investigation may be facilely accomplished 
through the use of another form of isentropic analysis 
devised by Starr [21]: the relative-motion chart. The 
aim of such a chart is to supplement the information 
given by streamlines at a single isentropic level. The 
relation between streamlines and contour patterns indi- 
cates whether there is upslope or downslope motion on 
the isentropic surfaces provided the wind near the 
isentropic level in question increases with height, as is 
generally the case. The function of the relative-motion 
chart is to give an approximation of the change in wind 
with height at the isentropic level being considered. 
OBSERVATIONS AND ANALYSIS 
Relative-motion charts are easily prepared, given the 
isentropic data. They could be drawn and transmitted 
from analysis centers as an additional tool for the use of 
the local forecaster. Such arrangements would benefit 
not only the synopti¢ meteorologist, but the research 
man as well, an important consideration since in the 
field of research, isentropic analysis is acknowledgedly 
of significant value. 
Conclusion 
In various specific contexts in this discussion of 
analytical techniques we have mentioned the value of 
the use of color in augmenting the clarity of analyses. 
Despite the habitual use of color on meteorological 
charts, its utilization has tended to be haphazard and 
accidental rather than systematized. To a surprising 
extent even simple uses of color have been neglected in 
the United States. The psychological effect of color and 
its use as an aid to analysis should in the future 
receive the attention it warrants. 
Another neglected problem is that of the ideal ar- 
rangement for an analysis center or forecast station. As 
far as the authors can discover, the results of compre- 
hensive studies of this subject have not been incorpo- 
rated into actual practice. The optimum height of 
working surfaces, lighting, best selection of furniture, 
and the arrangements of furnishings and charts are 
considerations which lie outside the field of meteorology 
proper. But seemingly minor factors such as these (or 
such as the use of color mentioned above) may con- 
tribute appreciably toward better analysis. In order to 
improve forecasts, these problems must be solved along 
with those of a more strictly meteorological nature. 
But beneath these specific analytical problems, and 
precluding thei solutions, he the broader barriers to 
rapid advancement in the field of meteorology as a 
whole. One of these fundamental obstacles is the con- 
fusion occasioned by the plethora of theories and oper- 
ational practices, attending the sudden multiplication of 
reliable meteorological instruments, which has pre- 
sented for the scrutiny of the forecaster an entirely new 
and unprecedented multiplicity of data. The other 
basic obstacle is the enigma of the processes involved in 
the general circulation of the atmosphere. Once a valid 
theory of this general circulation has crystallized, order 
should begin to appear in the present chaos of our 
secondary meteorological theories. However, until such 
time as this is accomplished, it behooves those of us 
concerned with analysis to follow up whatever lines of 
research seem promising, searching through meteoro- 
logical theory for effective applications to analysis and 
seeking to better our analytical techniques through ex- 
perimentation and critical discussions participated in 
by meteorologists all over the world. But despite our 
concern with the details of analysis, we must never lose 
sight of their dependent relationship to the larger and 
more fundamental concepts of meteorology. 
REFERENCES 
1. Austin, J. M., ‘‘Temperature Advection and Pressure 
Changes.” J, Meteor., 6:358-360 (1949). 
