544 
processes, which must ultimately be responsible for all 
air motions and are a determining factor for the form 
of the general circulation. What we have done is simply 
make a systematic analysis of data to portray as clearly 
as possible one important, but not patently apparent, 
attribute of the general circulation—namely, the angu- 
lar-momentum balance. This study attempts to show 
how the actual atmosphere attains an internal consist- 
ency in one important respect. 
What purpose can such information as this serve in 
the future of meteorological theory? The answer to 
this query is obvious. Once the announcement was made 
by Kepler that planets move in ellipses, any proposed 
dynamic theory of mechanics which would require them 
to move in significantly different paths was immediately 
pushed into the limbo. Likewise for the atmosphere 
any proposed rational theory for the general circulation 
which significantly contradicts the general outlines of 
the needed angular-momentum balance at once finds 
itself afflicted with a serious and perhaps even crucial 
drawback. On the other hand, the uses of such informa- 
tion need not be purely negative. The facts might well 
serve a& one guide (among many others) for the for- 
mulation of satisfactory rational schemes. 
What has been described is not a very profound con- 
cept, but merely a rather simple consequence of New- 
ton’s laws of motion applied to the atmosphere. The 
gist of the idea was presented many years ago, by 
Jeffreys in 1926. How is it then that it was permitted 
to lie fallow for so long a time? Aside from the lack of 
proper data, a contributing factor has doubtless been 
the preoccupation of research meteorologists with phe- 
nomena on a relatively local scale, this in turn bemg 
due to the limitation of our mental horizons to a scale 
commensurate with the daily weather map. 
One might well venture the guess that at present we 
have not attained even a measure of the tasks which 
confront us. And this statement is in no way intended 
as a repetition of a common platitude. We have not 
fathomed the profundity of our subject, let alone solved 
the fundamental problems. In the years to come, when 
our knowledge will have increased, we may in retro- 
spect wonder why we were so inappreciative of various 
gross and essential attributes of the general circulation. 
It would therefore be wrong and dangerous to post a 
sign along any plausible path of research which states 
“Thou shalt not enter here,” seeking thereby to channel 
activity along certain predetermined lines. True science 
tolerates no prohibitions, and in principle no servile 
adherence to tradition. Rather we must open up and 
exploit all possible new channels that appear reasonable 
in order that we do not miss important facts.* It is in 
THE GENERAL CIRCULATION 
this spirit that the writer would recommend the further 
exploration of the essential properties of the global 
circulation as we know it from observations with regard 
to such dynamic quantities as angular momentum, 
vorticity, kinetic energy, heat energy, geopotential en- 
ergy, and latent heat, so that we may find ourselves 
in a more advantageous position in formulating rational 
hypotheses. 
For the purpose of exemplifying further the sugges- 
tions previously made, let us consider in a general way 
their application to questions concerning energy in the 
atmosphere. Much of what has been written concerning 
this subject has been deficient in two respects. In the 
first place investigators have been prone to lump to- 
gether various diverse forms of energy indiscriminately, 
thereby losing the advantages to be gained from the 
fact that each form of energy is produced from and 
converted to other forms in its own characteristic 
fashion, permitting individual study. Likewise for each 
form there exist specific modes of transfer and redis- 
tribution. Unless these specific characteristics are sub- 
ject to scrutiny in detail, only very broad generalizations 
can be reached, which lack a keen enough resolving 
power to yield much that is new concerning the mecha- 
nism of the atmosphere. 
In the second place, as will be discussed presently, 
the modes of energy transfer within the atmosphere 
are so effective that no feature such as a cyclone can 
be treated independently without due allowance for 
exchanges of energy between it and the remaining 
atmosphere. It is therefore inappropriate to treat such 
a feature as in any sense a closed system. Modern trends 
in the literature are beginning to give proper cognizance 
to this circumstance, although much of the too- 
restricted point of view is still prevalent. Probably the 
only system which can be treated as a closed one 
(mechanically) is the atmosphere as a whole and even 
then it cannot be treated as closed from a thermody- 
namic viewpoint because of radiative exchanges of 
energy with the cosmic environment and otherwise. 
Proceeding now to a discussion of the kinetic energy 
balance of the atmosphere, it is worthy of note in the 
first place to observe that whereas angular momentum 
is a quantity which is conserved in the sense that no 
real sources of it can exist, kinetic energy on the other 
hand may appear or disappear because of transforma- 
tion processes involving other forms of energy. In other 
words, the flow and redistribution processes for kinetic 
energy are not source-free as is the case with absolute 
angular momentum. We may therefore say a priori 
that there is no reason to suppose that there may not 
exist in the atmosphere preferred source-regions for 
angular momentum about the earth’s polar axis. In effect this 
equation takes on the form of a continuity equation for ab- 
solute angular momentum. 
4. When one compares the general nature of the results of 
research in meteorology as reported in our journals with the 
nature of research communications in let us say chemistry, 
there is a fundamental contrast to be noted. In our field there 
is a great diversity of views expressed on individual topics. 
Often these views are in direct conflict. Also one gains the im- 
pression that there is less of the orderly progressive accumula- 
tion of knowledge. This phenomenon is doubtless due to the 
fact that meteorology is in a far different stage of development 
as a science. In the better sense of the word we are alchemists 
still in the process of groping for a common denominator of 
unifying principles. We must not relax but rather continue to 
stumble and grope with more determination. The writer has 
the immutable belief that a proper foundation does exist and 
will be found. 
