Editor’s Preface to 5th Edition 
NCEASING demand has again 
U induced the Society to extend 
this convenient booklet into 
a 5th revised and enlarged edition. The 
text of the 4th edition is reprinted with 
numerous secondary annotations and 
changes to indicate some of the present 
attitudes or practices that depart from 
those stated or implied in the previous 
editions. The practices in other coun- 
tries are so diverse that no special note 
of them could be taken, but extensive 
citations of foreign literature are 
given in the Bibliography. 
At the time the 4th edition appeared 
(Oct. 1938) a new technique and point 
of view, known as isentropic analysis, 
was under promising experimental de- 
velopment and it was anticipated by 
the authors and editor that any future 
edition of this “Introduction” would 
have to take account of the new method. 
Already in 1939 isentropic analysis was 
so generally practiced in U. S. A. that 
plans were laid to add an introductory 
chapter on the technique. Mr. Namias 
was engaged by Prof. Sverre Petter- 
ssen to prepare such a chapter for his 
excellent book “Weather Analysis and 
Forecasting” recently published. We 
are able to offer a slightly modified 
form of this chapter in our 5th edi- 
tion, through the kind permission of 
Prof. Petterssen and of the McGraw- 
Hill Book Co., Inc., of New York. 
The Bibliography in the 4th edition 
has been so widely appreciated that an 
effort is made to improve it materially 
in this new edition. Besides bringing 
it down to date, a great many more 
entries are added and the whole ar- 
ranged conveniently by _ subjects. 
Finally, additional illustrations are 
provided in the appendix. 
This opportunity has been seized to 
correct a few typographical and other 
errors which unfortunately passed in 
the 4th edition; the editor wishes to 
thank the numerous individuals who 
have kindly called our attention to 
errors and offered suggestions for 
improvement. The basic part of this in- 
troduction remains rather elementary, 
but many more technical annotations 
are provided for the numerous stu- 
dents who have the background to 
enter a little deeper into the subject. 
However, we have not attempted to 
enlarge the work into a textbook of 
synoptic meteorology. It is assumed 
that the reader is familiar with the 
elements of meteorology and with the 
general conception of the weather 
map as given in numerous and readily 
available textbooks, to which this 
booklet is only an adjunct of certain 
newer topics not particularly well- 
treated outside a few technical and 
expensive works. 
The material available for direct 
analysis of upper-air conditions has 
lately reached a new high. There are 
now 34 regular aerological stations in 
the U. S., mostly using radiosondes, 
the largest network of its kind in the 
world and in history. The adequate 
use of such data in forecasting is being 
tried here for the first time anywhere 
and will call for an increasingly quan- 
titative and physical approach. 
The editor wishes to acknowledge 
the very generous assistance in read- 
ing proof and valuable advice on 
many points given by Prof. Charles 
F. Brooks, Secretary of the Society, 
who has handled the arrangements 
for publishing this work. Thanks are 
due Miss Edna Scofield for aid in 
editing and reading proof.—Robert G. 
Stone, Sept. 1940. 
