West Wind lost –
cut off (2_12)
All color graphics are not shown in the book – click to enlarge
Weather from normal to arctic
conditions of the year 1939 were close to usual before WWII started on
September 1st. On the basis of previous annual statistics nothing
abnormal was expected. No one suspected that anything concerning weather
could go wrong with the first war winter. It is an acknowledged fact that
temperatures had been rising steadily in
since the end of World War I. Winters previous to 1939 were all normal.
The winter of 1938/39 had been mild except for a brief cold spell in
December 1938 that lasted from 15 to 20December only and was fully
replaced by warm Southwest winds beginning January 6, 1939. However, if
there was a contribution, it was presumably El Niño,
which is given reasoning in the following paragraph. But no one expected
or imagined a much different situation twelve months later. Only four
months after Hitler had started WWII, the weather in
became ‘violent’ with floods, storms, snow and icy conditions.
From the North Cape to the Mediterranean the weather statistics described
, Southeast England,
, and presumably the Baltic countries as experiencing the coldest winter
in more than 100 years. (A)
details: (A) Arctic Conditions, 2_11.
December 1938 and was El Niño involved?
gives a detailed assessment of the severe December 1938 cold spell. This
cold air from the ‘
(Pechorskaya Guba)’ seems to have had other causes than the emerging
arctic conditions in December 1939. But even if they did not, this could
be used as a contributing piece of evidence. The December 1938 event was
short. Actually, the winter of 1938/39 was mild. That a ‘repetition’
did not occur in December 1939 indicates that the underlying climatic
conditions (North Sea and Baltic Sea) had changed within only three months
of the start of war so much that the weather in Western and Northern
Europe could not return to ‘normal’, viz previous winter conditions.
back to the ice age in winter 1939/40?
this happen? What caused the weather to play havoc? Why was
thrown so easily back into the ‘ice age’? This section presents the
viewpoint that the war at sea was the main cause that changed the weather
. The main theses are:
I: During autumn and winter the warm water of the North- and Baltic
Sea (in comparison to the coldness of the continental land masses due to
lack of sunshine) attracts the ‘west wind drift’*) on which
cyclones travel eastwards across Western Europe, blocking continental high
pressure systems with cold air from moving to West-Central Europe or at
least keeping them at bay. The earlier and/or more the stored summer heat
of these seas is diminished by force earlier in the winter, more
forcefully continental anti-cyclones will take control, which may reach
the Atlantic coast of the
. Effective means of ‘squeezing’ heat out of the sea are wind, waves
and all military and naval activities. (A)
09 December 1939
09 December 1939
12 December 1939
details: (A) North Sea cooling, 2_16,
and Baltic Sea cooling, 2_17.
meteorologists prior WWII used the term ‘west wind drift’, a term
which is today commonly used for Antarctic circumpolar wind and current.
II: The flow of ‘normal’ weather processes in the atmosphere
depends on the balance between humidity in the air and its concentration
and transport by low-pressure systems, or vice versa, the dry air of
high-pressure systems. This balance can be easily affected by reducing the
amount and concentration of ‘water’ in the atmosphere. That this
definitely occurred along and behind the Western Front of several hundreds
km length from Dunkerque (France) and
) is explained in section: Contributing matters. (A)
details: (A) Rain-Making, 2_31; USA
dried out, 2_32, and War in
developments in autumn 1939 in focus
chapter proposes to show that the meteorological developments since
September 1939 indicate clearly that conditions of the North Sea helped
pave the way for plunging North-Western Europe, from
to the Baltic Countries into the coldest year since early 19th
century. Military activities changed the seawater temperature structure of
’s northern seas, ‘forced’ humidity out of the atmosphere at the
Western Front. This event did not disappear without leaving any traces. To
prove this point the daily “weather analysis” reports of the Deutsche
Seewarte, as part of the daily weather records, will be used to show that
during the period from September to December 1939, there were indications
that the weather in Middle Europe did not behave according to the ‘rules
of average’. The aim is to adduce evidence to prove that this winter in
question did not emerge ‘out of the blue’ but developed gradually and
due to anthropogenic making.
of Winter analyzed by Neue Zürcher Zeitung
analysis by the Neue Zürcher Zeitung (NZZ, 14 January 1940) the
development of cold conditions happened as follows:
cold which flooded the whole of
in the course of this week was by no means an accidental phenomenon that
set in surprisingly. It rather constitutes the peak of a development which
had its beginning in the first week of December. Towards its end high
pressure began to stabilize in North and Middle Europe, keeping away the
low Atlantic cyclones from the continent and diverting them mainly through
Greenland and Iceland waters to the Sea….As soon as occasional Atlantic
depressions moved East through the North and Baltic Sea, they were
immediately replaced by entry of cold air from the Greenland area.”
convincing is the assumption made shortly after WWII, that the “shift”
to the severe winter conditions of 1939/40 was caused by a sudden build-up
of a cyclone off the Lofoten on 20th December 1939.
role did El Niño play?
the scientific approach of this work is to elaborate historical data and
views, an exception shall be made with regard to recently published
articles concerning the long-distant effect of El Niño.
graphic – not enlargeable
Stefan Broennimann and his colleagues inquired the causation of the
extreme European winters 1940-42.
We fully support the conclusion “that the global climate anomaly in 1940
to 1942 constitutes a key period for understanding of large scale climate
variability”, but have reservations in following Broennimann et. al.
linking the arctic war winters decisively to El Niño.
As this is not the place to reply in detail, only a brief comment shall be
is a long established fact that El Niño events can be linked to unusual
short-term weather deviations in distant regions, but
is only remotely affected. During the last 150 years the
experienced about 40 El Niño events.
Some severe winters concede with events, some not (e.g. 1916/17, 1928/29).
Nevertheless, modest influence cannot be denied outright. In July and
August 1939 an El Niño event reached its height having caused the best
vegetation in Peru for 14 years,
but the 1939 El Niño was not
In autumn 1939 the event had already reached the culminating point.
in 3 to 7 years interval, a warm water pool that causes the
El Niño effect generates in the western Pacific
and moves along the Equator toward Central and
. The moving time is about nine months,
while Dake Chen et. al.
concluded recently that the motion of the pool is causing changes in the
atmosphere and not vice versa. Thus the brief cold spell in Northern
Europe in December 1938 (see above) could possibly have been caused by a
warm water pool that started to leave the western Pacific in late 1938 to
become El Niño 1939 a couple of months
After all, the warm water pool is relatively small, presumably of a volume
corresponding to a few times of water masses held by the North Sea when
traversing the Pacific starts, respectively an area comparable to that of
Australia, to a depth of 50 to 100 metres at a later stage. The extra heat stored is substantial but limited.
The temperature may be up to 4°C higher than usual. Correspondingly the
time duration for causing local and long distant effects is limited. The
El Niño culminated in late summer 1939. Thereon
receded, as the full cycle is 1 to 2 years. Even if the water pool still
held any surplus heat it had little if anything to do with the record
during the fourth quarter of 1939 and the glacial cold spell all over the
Northern Hemisphere in January 1940 and the arctic winter
lasting until March 1940, which is elaborated in more than a dozen
details: (A) USA dried out, 2_32.
are even less reasons to assume that the equatorial Pacific had anything
to do with the 2nd and 3rd glacial war winter in
either. For long many scientists claim that there had been a prolonged El Niño lasting from 1939 to
1942. This has never convincingly been established. The Pacific does not
provide the “physical conditions” – as explained in the previous
paragraph- for a prolonged eastward flow of warm water. As far as
observations between 1940 and 1942 might have indicated to El Niños
actual causation might be quite different. The claim of prolonged El
Niño condition is largely based on Sea Surface
Temperature (SST). Due to the war conditions these data are not reliable,
neither for the Pacific,
nor for the
Furthermore should be considered that extreme weather conditions in Europe
caused by cooling the North and Baltic due to naval warfare (2_16),
(2_17) could also produce a long distant effect, e.g. in the Pacific
region, which may look like as belonging to an El Niño. It is critical to
regard the El Niño of 1939 as a
prolonged event until 1942. If there was no such prolongation then the Broennimann’s
theses on El
Niño relevance for arctic war winters 1940-42
in Europe  would require further explanation, as well
the fact that other severe winters occurred outside the event period (e.g.
1916/17, 1928/29). Further discussion in this paper shows that the making
of the arctic winter 1939/40 came from regional conditions leaving little
if any role for the Pacific to intervene in high Northern Hemisphere
start of the winter of 1939/40 elaborated
weather analysis by the NZZ on 14th January 1940 came to the
conclusion that the origin of the cold wave across
could be traced back to the first week of December 1939, even though the
actual process had started much earlier. Though the NZZ assumed the
change in weather conditions to have taken place since the 1st
week of December 1939, a high pressure kept Atlantic cyclones away from
North and Middle Europe latest since October 1939. To prove this theory
this paper will depend to a large extent on daily weather reports of
German meteorologists at the Seewarte in
during the first four war months, viz. September - December 1939.
discussing the cooling of Europe in late 1939, a brief assessment of the
general conditions during the year 1939 will be presented in the form of
weather analysis clippings by meteorological services in respect of
compiled by the author. This is to show that the climatic conditions
during the first eight months of 1939 until the end of August had been
exceptionally normal without any significant deviation. This means that
the Second World War started on a ‘clean sheet’ of normal climatic
Weather during 1939 – Four country
following four extracts should be read keeping in mind that WWII started
in September 1939 and that climatic conditions were not necessarily
‘normal’ during the final four months of the year or first four months
of the war, i.e. September to December 1939. Particularly the record rain
area stretching from
from September to November 1939 is already war related. (A)
details: (A) Rain-Making, 2_31.
The weather on the
weather conditions were almost average, the spring again had a succession
of warm spells interspersed with brief cold spells. After a warm and sunny
start in early June, the summer was comparatively sunshine-free with an
early autumn, with the exception of a warm period in August and early
September. As in previous years, November was very warm. There were,
however, very few gales. There was a notable above average rainfall in the
South-eastern districts and below average in the North-western districts.
Rains, far in excess, occurred in the Southeast. Actually, in October 1939
recorded excess rainfall of more than three times the average and November
recorded twice the average.
The weather in
meteorological analysis for the months January - June 1939 notes a weather
with a tendency to be mild and partly too wet but mentions nothing special.
During the months of July and August 1939, the weather in
was regarded as too warm and too wet. A summary for September indicates
that the month was a little bit too cold in the southern one-third of the
‘Reich, and it was by far too wet from the upper and middle Rhine area
(Schlesien). October was colder for the whole of the ‘Reich’ but
extremely wet in the Southern part and dry in the North. November was
generally too warm and too wet. December was generally too cold, but it
was too wet only in Saxony and
The weather in
of the year 1939 was marked with mild winter weather with low wind
cyclones and excessive rain. Spring months witnessed changing pressures
with partly dry spells. The summer months were dominated by a low-pressure
moving northeast, which brought along high precipitation to the Southwest
of Sweden, in particular. Warm and dry summer weather appeared in August,
when a high pressure dominated, which lasted through September. Then the
weather became wetter and wetter with storms, which are usually rare
during the season, becoming more frequent.
however, was characterized by several highs consequently making the
weather relatively cold and dry. During the remaining months of the year
there was a rather large number of lows, carrying along precipitation as
well as storms. The last week of the year was marked by some lows –
moving southeast – and brought along an exceptionally strong cold for
the whole country.
The weather in
a very rainy year. In Zürich it was the year with the highest
precipitation for the last thirty years. The sunshine was one third less
than expected. For the last fifty years no other year had witnessed less
sunshine as 1939. Only January and April had normal sunshine; farthest
away from normal were May and October, which reached a degree of
cloudiness like never before. Compared with these extremes the average
annual temperature was quite normal. As to the 75 year average, the
average of 8.8°C of 1939 even showed a slight increase in the level of
warmth by about one tenth of a degree. Still, 1939 was the coldest among
the past six years.
Source: Neue Zürcher
Zeitung; Montag, 8 Januar 1940
should be noted that the high precipitation is due to the heavy rain since
the war started. The triangle
, e.g. Freiburg/Breisgau, had 30 rainy days in October 1939. (A)
details: (A) Rain-Making, 2_31.
The flow of Atlantic air
weather conditions in
are determined by the cyclonic west-wind climate, which is dominated by
the movement of maritime air masses from west to east, most significantly
during the winter season. German meteorologists called it west-wind-drift
(WWD) until the 1940s. Particularly sensitive to the WWD are Northern
Europe, north of the English Channel, the Alps and the
. Since sunshine is less during the winter months, heat stored by the
ocean or seas contributes to
’s usual mild winter weather conditions. For cyclones generated in the
middle of the North Atlantic, south of
, the common axis for going east would be via
, the North Sea and
. As long as the flow of maritime air from the Atlantic is moving this
way, the climate in
is moderate and the flow of continental air is reduced. This common
climatic mechanism was considerably reduced in respect of all countries
bordering the North and
in late 1939. Although the
was not less active as usual, the low-pressure systems moved less and less
along the common WWD.
to the Neue Zürcher Zeitung (14 January 1940) the meteorological
conditions for the early cold in January 1940 could be traced back to the
first week of December 1939. (A) Indeed, on the 8th of December
the situation was conducive for an early winter and presumably cold start
into the winter season, when a solid high-pressure bridge stretched from
Scandinavia to France (see map above). Such a situation cuts Middle Europe
off from the weather making process in the
details: (A) above page 25.
It took only two weeks for
to enter into a very severe winter. The weather chart of the 21st
December 1939 (see p. 35) showed that a high pressure with 1,033mb had
taken position over Central Europe (
), with three cyclones on the periphery; one the off Lofoten (970mb); one
in the middle of the North Atlantic, south of
(980mb); and one off the coast of
(1,010mb). The corridor via the
was definitely closed for some time. The ‘too cold’ water body formed
a barrier preventing Atlantic air to flow along the common WWD. That this
process had started much earlier than in December 1939 is discussed
hereafter. This discussion is based on the daily weather analysis of the
German meteorological service, the “Seewarte”.
average? – September 1939 – First signs?
the first few days of September 1939 the weather in Western Europe was
influenced by a high pressure over
. Except for a mixed front line (warm and cold) running from Bergen,
Jutland, Basel, the Adriatic Sea, Malaga and out into the North Atlantic
on September 5, the dominance of the high pressure remained until
September 9 when a cyclone passed Scotland, entering the North Sea
(September 11-13). The movement of the cyclone from Jutland, through the
German Bight to the coast of the
and then to
seems to have puzzled the analyst as recorded in his assessment on
September 12th and 13th. At least, he spares no efforts to
explain this event. What this cyclone may show is that the WWD still
remained functional two weeks after the war had started. Actually, the
cyclone had been located south of
on September 9th (1,005mb), Northwest off
’s coast on September 10th (1,005mb), moving via the Northern
North Sea to
(1,000mb) on September 11th. ‘Normally’ the cyclone would
have moved via the Kattegat to the Southern Baltic, unless a significant
temperature difference between the land (cold) and the water of the North
Sea (warm) had attracted it to take the southerly route.
Book image – not enlargeable
It could well be possible that the cyclone’s movement was determined by
military activities in the Helgoland Bight and the laying of large mine
fields in the Middle of the North Sea (called: ‘Westwall’).
details: (A) Sea mines, 2_14.
the next two weeks the daily weather charts show quite solid proof of the
existence of a high-pressure area between
from September 16 – 28. Most significant comments of the Seewarte
analyst are as follows:
September 1939; Cyclonic activities over the
area (Nordmeergebiet) are intensive. The west-drift in the North will
consequently move more and more to the South.
September 1939; With the advance of Atlantic air into Middle Europe a more
forceful cyclone can develop along this channel (Rinne) which could extend
its influence in the Middle Europe later.
The last two extracts show the high expectation that cyclonic activities
in Middle Europe will resume soon, which did not occur as indicated in the
following extract one week later.
The analyst wonders
– October 1939
When the month of October was over, the Seewarte analyst came to the
conclusion (2 November 1939) that in the current year the
west-wind-drift (WWD) of the temperate zones was very underdeveloped
and was missing completely in
. It was not the first time that the daily weather analysis had given
an indication about the weakness of the WWD in autumn 1939 , e.g.:
1939; Along with a peripheral low, the first effective gust of maritime
air has reached
. A continuous WWD, however, cannot be expected yet.
October 1939; A broad high-pressure bridge has formed between the Atlantic
high. Again this results in a weather situation like those, which have
been witnessed frequently before during corresponding months, viz. a
high-pressure zone moving from the Atlantic via Southern Scandinavia to
, with low-pressure disturbances to the North and South of it.
1939; Usual weather is changing now and the high pressure bridge which
high with the West Russian high is broken up. A transition to a west wind
situation is on the verge of the German seas.
October 1939; Since a high pressure bridge from Middle Scandinavia to
remains, a further stream of cold air from the
area (Nordmeerraum) is cut off.
October 1939; Analysis of the weather chart for November 2reads as follows:
lies in the South (Southern
part) of the high-pressure area and mostly experiences winds coming from
East till North (
directions), which is clearly shown by the climatic data for last October:
reported winds from the
North-Eastern quadrant on almost two thirds of the dates observed (33%
easterly winds out of 65%) while North-Eastern winds accounted only for a
quarter (26%) of several previous years’ averages. Otherwise most
frequent direction of the wind – South-West (24%) – accounted for 9%
of all cases. Thus the observations at this station alone show what the
weather charts of an extensive area will obviously indicate as well.
This is a very strong and clear indication that huge air masses moved
, presumably caused by unusual high evaporation in this sea area.
While the water of the North Sea was ‘stirred and turned’ the
‘steam’ rose upwards into the sky, causing air to flow in from
Easterly direction, which subsequently prevented low-pressure systems
to travel along the west-wind-drift channel via the North Sea and
Central Europe into the eastern hemisphere.
November 1939 – Average not returned
the next four weeks are mixed. Four statements made during the month may
illustrate the situation as seen by the analysts who thought them worth
mentioning at that time.
November 1939: It appears that now – like in many earlier years – a
WWD with lively cyclone activities will begin to move over
at about the middle of the month.
1939; It seems that a mainly sectional circulation is going to take over
in the general weather situation: its pressure field will be characterized
by a long high pressure zone – Azores –Southern Germany –
– and WWD-like turbulence activity in the North of these regions.
November 1939; West Siberian high is slowly retreating towards the East
thereby allowing the disturbance coming from the West to penetrate still
deeper into the regions of European Russia.
30 November 1939; A very distinct west wind weather situation rules
over North and Middle Europe.
In summary the expectations of the weather analyst for ‘lively
cyclone activities’ did not materialize. Seawater changes by devastating
war machinery were not imaginable by weathermen then.
The drift is gone – December 1939
– The ice age returns
The first few days of December see attempts by rather weak cyclonic storms
to reclaim their common path of travel from the
to the Eastern hemisphere. By 7th December 1939 a high pressure
(West Germany/Belgium), stretching to
, the ‘last straw’ that led to a severe winter condition, as analysed
by the Neue Zürcher Zeitung, and reproduced above, (NZZ, 14 January
1939). Four further excerpts from the daily Seewarte analysis demonstrate
how the ‘Seewarte’ civil servant on duty judged the developments.
21 December 1939 (not enlargable)
21 December 1939
25 December 1939
December 1939; Quite distinct Atlantic frontal zone of the last few days
8 December 1939; It appears that the influx of warm air from the West is
stronger than the retreating stream of cold air so that the high pressure
bridge might stay, although the English frontal zone is currently
progressing towards the East ever so slowly.
19 December 1939; A high-pressure ridge stretches….(etc). These
conditions, however, are not likely to exist. The same pressure ridge is
attacked from two sides and has gained more than 10mb in the past 24 hours….
21 December 1939; A high pressure area that yesterday lay over the
Northern coast of
, lies today over
with a central pressure of 1,034 mb. The heavy fall in pressure over the
area (Nordmeerraum) has produced a low there.
Since this date the West Wind Drift was defiantly barred from
-see previous image-box-
The foregoing investigation stressed the significance of the
observed change of wind direction in
during October 1939. Wind direction had dramatically changed from
prevailing SW winds to dominating NE winds.
At this stage it might be worth noting the research made by
for Kew Observatory (London) in the early 1940s, that of the prevailing
wind directions in South-West England during 155 winters from1788 to 1942
only 21 had easterly resultants whereby the few winters 1814, 1841, and
1940 had resultants from NE to ENE, meaning northerly than East. Another
little number of winters since 1841 (1845,1870,1879, 1891, 1895, 1904,
1929) had prevailing SSE to ESE. With the exception of the winters 1801
and 1804 all of these 21 winters with predominant easterly winds had a
temperature below average (40,1°F; 4,5°C). While eleven of the above
winters had means between 34°F and 36°F, only few westerly resultants
had means lower than 37°F, these being 1820,1830,1847,1855 and 1886.
In summary it can be established, that winter 1940 clearly
played in the league of the Little Ice Age, being the only winter with
wind from the NE quadrant since the end of the Cold Medieval Age Period.
That had little to do with distant El Niño
but a lot with the just started war at sea.
1939, on the question whether the usual west wind situation was returning
to normal, the analysts concerned may have become frustrated over the
delay. On 19th December it was regarded certain that the ridge
would cease, but the belief was in vain. The two low pressures may have
looked strong enough to fulfil the task, but what the analysts did not
know was that the regional seas were not able to act in unison. Only two
days later Central Europe was solidly under the control of a high pressure
bringing in air from Greenland or Russia’s North. The North and Baltic
Sea had lost too much of their heat capability to steer
through a moderate winter. The coldest winter was due. (A) The war at sea
made the seas bend the weather in
according to its will, acting swiftly to stir and shake. (B)
details: (A) Winter 1939/40, 2_11;
(B) North Sea cooling, 2_16, and
Baltic Sea cooling, 2_17.
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