An Introduction to the Study of Air Mass and Isentropic Analysis

246 Pages·1940·17.123 MB·English

by  Jerome Namias

A
I^AfiTuivw.*^
An
Introduction to the Study of
Air Mass and Isentropic
Analysis
By
JEROME NAMIAS
Fifth Revised and Enlarged Edition
with
Contributions
by
TOR BERGERON
BERNHARD HAURWITZ
GRAHAM MILLAR
ALBERT SHOWALTER
K.
ROBERT STONE
G.
AND
HURD WILLETT
C.
Edited by
ROBERT STONE
G.
October, 1940
E AMERICAN METEOROLOGICAL SOCIETY, MILTON, MASS.
Price $1.25, postpaid
Given in Loving Memory of
Raymond BraisUn Montgomery
Scientist, R/VAtlantis maiden voyage
2 July - 26August, 1931
Woods Hole Oceanographic Institution
Physical Oceanographer
1940-1949
Non-Resident Staff
1950-1960
Visiting Committee
1962-1963
Corporation Member
1970-1980
Faculty, New York University
1940-1944
Faculty, Brown University
1949-1954
Faculty, Johns Hopkins University
1954-1961
Professor ofOceanography,
Johns Hopkins University
1961-1975
An Introduction to the Study of
Air Mass and Isentropic
Analysis
By
JEROME NAMIAS
Fifth Revised and Enlarged Edition
with
Contributions
^5 TOR BERGERON
^S°
BERNHARD HAURWITZ
^m
^ GRAHAM MILLAR
x^SP ALBERT SHOWALTER
K.
::i^g§ ROBERT G. STONE
|^=
AND
^^3
HURD WILLETT
G.
Edited by
ROBERT STONE
G.
October, 1940
THE AMERICAN METEOROLOGICAL SOCIETY, MILTON, MASS.
Price $1.25, postpaid
The Previous Editions of This Work
Appeared Under the Title
"An Introduction to the Study of Air Mass Analysis"
First Edition Sept., 1934-May, 1935
. .
Second Edition September, 1935
. . .
Third Edition August, 1936
. . .
Fourth Edition October, 1938
. . .
TABLE OF CONTENTS
Pages
Editor's Preface v-vi
Introduction . 1
I. Conditions of Atmospheric Stability: Lapse Rates . . 1-5
II. Conservative Properties of Air Masses 6-12
—
III. The Rossby Diagram Plotting Routine .... 12-19
—
IV. The Rossby Diagram Interpretation 20-24
—
V. Elements of Frontal Structure The Warm Front 24-28
.
—
VI. Elements of Frontal Structure The Cold Front 28-31
. . .
VII. Elements of Cyclonic Structure 31-36
The Norwegian Wave-Theory of Cyclones, by B. Haurwitz 37-45
. .
Frontal Waves, by T. Bergeron 45
Sources of Energy for Extra-Tropical Cyclones, by T. Bergeron 45-46
A Note on Dynamic Anticyclones and Cyclones, by R. G. Stone 46-50
The Role of the Tropopause in the Dynamics of Extra-Tropical
Disturbances, by T. Bergeron 50
VIII. The Tephigram 50-55
Radiometeorograph Soundings in the Middle North Atlantic
(after Durandin) 48-49
. .
A Note on Estimating Conditional and Convective.In.sta.bili.ty
FROM THE Wet-Bulb Curve, by R. G. Stone 55-60
IX. Synoptic Aspects of the Thunderstorm 60-68
Airplane Soundings Illustrating Convection (after.Ko.chan.ski.) 68-71
The Ice-Nuclei Theory of Rainfall, by R. G.. S.tone.... 72
Hail Forecasting (after United Air Lines) 72
—
IV
Pages
Characteristic Properties of North American Air Masses, by
H. C. WiLLETT 73-108
Major Frontal and Air Mass Zones of the Earth, by
T. Bergeron 108
......
Further Studies of American Air Mass Properties, by
A. K. Showalter 109-113
. .
—
Illustrations: 113-135
Dust Storm (after Parkinson) 114-115
Flood Rains (after Minser; Byers) .... 116-llT
Fronts and Aircraft Icing (after Minser) 118-121
Bergeron's Model of the Warm-Front-Type Occlusion 122-124
.
Spring Showers (after Botts) 125
Winter Cyclone with Dust ^Storm (after Parkinson) 126-127
.
Maps and Cross Sections of Fronts; Aircraft Icing
(after Minser) 128
A Succession of Polar Air Masses; Weather Maps and
Cross Sections for Nov. 30 Dec. 2, 1938 (after George
and Elliot) 129-131
A RossBY Diagram (after Tu) 131
Synoptic Charts Showing Winter Cyclones (after Pierce;
Dorsey) 131-135
X. Isentropic Analysis 136-161
ISENTROPic Analysis of a Thunderstorm Situation, June 22-27,
1937 (after J. Namias) 161-167
Analysis of the Rainfall Situation over the Western States,
May 6-7, 1938, by Means of Air Mass and Isentropic Charts
(after Weightman) 168-171
Examples of Upper-Air Cross-Sections Showing Interpretations
OP the Tropopause, etc 172-175
A Bibliography for Synoptic Meteorologists, by R. G. Stone 176-226
.
Addenda to Bibliography 227
Glossary of Elementary Terms Used in Articles in I to IX . . 228-232
—
Corrigenda for "An Introduction to the Study of Air Mass and
IsentropicAnalysis/' by J. Namias and others, 5th ed.
Page 5, table at bottom of page, lines under "Condition" and "Type of equi-
librium", should be deleted and the following should be substituted (the
preferred terminology is italicized:
a< (Absolutely) stable
ft
—
a B Neutral for saturated air (equal to wet-adiabatic
lapse rate)
y3<a<y (Conditional:) stable for dry air, unstable for
saturated air.
=
a y Neutral for dry air (equal to dry-adiabatic lapse
rate)
y <a < 3.42 C° per100m (Absolutely) unstable (but not self-starting)
a= 3.42°/100m Upper limit ofmechanical stability
[a> 3.42"100 m Mechanicalinstability, orauto-convective gradient
(self starting; hence this is not an equilib-
rium)
]
Page 6, col. 2, line 8 of footnote, "J.-J. Jang" should read "Jaw."
Page 14. col. 1, line 11, "r/Pi"-^" shouldread "T/p."'^"
Page 14, col. 1, line 18, "wet-bulb temperature" should read "wet-bulb poten-
tial temperature."
Page 69, line 7, "Su" should read "Sc."
Page 71, top, line 4, delete "warm."
Page 150, col. 2, line 4, "stream function" should read "isentropic accelera-
tion potential" (see Bulletin A. M. S., Jan. 1941, p. 45).
Page 172, line 18 (in fine print) "frontal at" should read "frontal topogra-
phy at."
Page 174, line 9, "15 km" should read "18 km or higher."
Page 174, line 10, "by10mb"shouldread"by9mb."
Page 175, line 1, "In Fig. 6, shown above is" should read "Fig. 6 above is". . .
Page 175, line 3, "tions shows" should read "tions. It shows."
Page 228, 2nd col. line 34, "to dry air" should read "to saturated air;" line
33, after "entire" insert "originally stable".
Page 229, 2nd col., lines 2 and 3 from bottom, "decreases" should read
"increases."
Page 232, 2nd col., 3rd line from bottom delete "equal".
[Supplement to the June 1941 Bulletin of the American Meteorological Society']

—
Editor's Preface to 5th Edition
UNCEASING demand has again correct a few typographical and other
induced the Society to extend errors which unfortunately passed in
this convenient booklet into the 4th edition; the editor wishes to
a 5threvised and enlargededition. The thank the numerous individuals who
textofthe4th editionisreprinted with have kindly called our attention to
numerous secondary annotations and errors and offered suggestions for
changestoindicate someofthepresent improvement. Thebasicpartofthisin-
attitudes orpractices that departfrom troduction remains rather elementary,
those stated or implied in the previous but many more technical annotations
editions. The practices in other coun- are provided for the numerous stu-
tries are so diverse that no special note dents who have the background to
of them could be taken, but extensive enter a little deeper into the subject.
citations of foreign literature are However, we have not attempted to
given in the Bibliography. enlarge the work into a textbook of
At the time the 4th editionappeared synoptic meteorology. It is assumed
(Oct. 1938) a newtechnique and point that the reader is familiar with the
of view, known as isentropic analysis, elements of meteorology and with the
was under promising experimental de- general conception of the weather
velopment and it was anticipated by map as given in numerous and readily
the authors and editor that any future available textbooks, to which this
edition of this "Introduction" would booklet is only an adjunct of certain
havetotakeaccountofthenewmethod. newer topics not particularly well-
Alreadyin1939isentropic analysiswas treated outside a few technical and
so generally practiced in U. S. A. that expensive works.
plans were laid to add an introductory The material available for direct
chapter on the technique. Mr. Namias analysis of upper-air conditions has
was engaged by Prof. Sverre Petter- lately reached a new high. There are
ssen to prepare such a chapter for his now 34 regular aerological stations in
excellent book "Weather Analysis and the U. S., mostly using radiosondes,
We
Forecasting" recently published. the largest network of its kind in the
are able to offer a slightly modified world and in history. The adequate
form of this chapter in our 5th edi- useof such datainforecasting is being
tion, through the kind permission of tried here for the first time anywhere
Prof. Petterssen and of the McGraw- and will call for an increasingly quan-
Hill Book Co., Inc., of New York. titative and physical approach.
The Bibliography in the 4th edition The editor wishes to acknowledge
hasbeenso widelyappreciated thatan the very generous assistance in read-
effortis made to improve it materially ing proof and valuable advice on
in this new edition. Besides bringing many points given by Prof. Charles
it down to date, a great many more F. Brooks, Secretary of the Society,
entries are added and the whole ar- who has handled the arrangements
ranged conveniently by subjects. for publishing this work. Thanks are
Finally, additional illustrations are due Miss Edna Scofield for aid in
provided in the appendix. editing and reading proof. Robert G.
This opportunity has been seized to Stone, Sept. 1940.
From the Preface to the 4th Edition
When these sketches were first pre- of airport and city offices of the
pared it was thought that the sub- Bureau, and many of their personnel
ject would develop so rapidly that can now produce or interpret analyses
any attempt to simulate a well- acceptably, while at the Central Office
rounded and comprehensive treatise, in Washington competent and funda-
even for beginners, would not be mental research is being carried on.
justified nor feasible. Needless to say (The problem of rapidly training a
the continued warm response and wide large organization in such a different
influence which the work has had has technique is admittedly difficult).
left the authors and editors with a The present "Introduction", how-
sense of responsibility for which they ever, should not be regarded as one to
had not bargained. The authors feel the whole field of synoptic meteor-
that most of the early principles of ology. For such a serious ambition
air mass analysis still bear a funda- one should study physical meteorology
mental value for synoptic practice, so as well, and there are excellent gen-
that extensive revisions have not been eral texts such as Humphreys' "Phys-
necessary in this new edition, though ics of the Air", Brunt's "Physical and
references are made here and there to Dynamical Meteorology", Taylor's
some of the points that have been "Aeronautical Meteorology", "Byers'
particularly altered or questioned in "Synoptical and Aeronautical Mete-
light of more recent developments. orology", [and now (1940) also Pet-
From the practical point of view, terssen's "Weather Analysis and
the beginner in America now has Forecasting", Sutcliffe's "Meteorology
much better opportunities to "pick up" for Aviators", and "The Admiralty
experience through his own efforts Weather Manual",] to lighten the
than when this "Introduction" first road. But to that large audience
appeared over three years ago, when which desires only a brief, authorita-
no competently analyzed air-mass tive, and inexpensive "first reader"
weather maps were available outside in this fascinating concrete way of
of a few institutions and special serv- looking at the weather, this booklet
ices and none to the public. At pres- is offered again in the hope that
ent, thanks to the remarkable changes it will continue the instrument for
in U.S. iWeather Bureau practice wide dissemination of modern me-
since 1934, such maps may be in- teorological principles which it has
spected by anyone at a large number been.—Robert G. Stone, Oct. 1938.