lost – Europe cut off (2_12)
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 Europe 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 Western Europe became
‘violent’ with floods, storms, snow and icy conditions. From the
North Cape to the Mediterranean the weather statistics described North
Germany, Holland, Southeast England, Denmark, Sweden, and presumably the
Baltic countries as experiencing the coldest winter in more than 100 years.
details: (A) Arctic Conditions, 2_11.
December 1938 and was El Niño
gives a detailed assessment of the severe December 1938 cold spell. This
cold air from the ‘Petschora Basin (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?
could this happen? What caused the weather to play havoc? Why was Europe
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
conditions in Europe. 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 British Isles. Effective means
of ‘squeezing’ heat out of the sea are wind, waves and all military
and naval activities. (A)
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 Emden (Germany) to Basel (Switzerland) is
explained in section: Contributing matters. (A)
details: (A) Rain-Making, 2_31; USA dried out, 2_32, and War in China,
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 Southern England to
the Baltic Countries into the coldest year since early 19th
century. Military activities changed the seawater temperature structure of
Europe’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.
analyzed by Neue Zürcher Zeitung
an analysis by the Neue Zürcher Zeitung (NZZ, 14 January 1940) the
development of cold conditions happened as follows:
cold which flooded the whole of Europe 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
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.
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 Northern Europe is only remotely affected. During the last
150 years the Pacific Ocean 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 particularly anomalous.
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 north of Indonesia and moves along the
Equator toward Central and South America. The moving time is about nine
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 later.
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
1939 El Niño
culminated in late summer 1939. Thereon El
Niño 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
in the USA during the fourth quarter of 1939 and the glacial cold spell
all over the Northern Hemisphere in January 1940 and the arctic winter
Europe 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
Europe 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 North Atlantic.
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 weather affairs.
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 Europe 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 Hamburg 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 North
Europe 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
during 1939 – Four country assessment
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 Dresden and Basel to London from September to
November 1939 is already war related. (A)
details: (A) Rain-Making, 2_31.
on the British Isles during 1939
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
Southeast England recorded excess rainfall of more than three times the
average and November recorded twice the average.
in Germany during 1939
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 Northern Germany
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
towards Silesia (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 Silesia.
in Sweden during 1939
start 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.
in Switzerland during 1939
was 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.
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 Switzerland, France and Germany, e.g.
Freiburg/Breisgau, had 30 rainy days in October 1939. (A)
details: (A) Rain-Making, 2_31.
flow of Atlantic air
weather conditions in Europe 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 Black Sea. Since sunshine is less during
the winter months, heat stored by the ocean or seas contributes to
Europe’s usual mild winter weather conditions. For cyclones generated in
the middle of the North Atlantic, south of Iceland, the common axis for
going east would be via England, the North Sea and Northern Germany. As
long as the flow of maritime air from the Atlantic is moving this way, the
climate in Western Europe 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 Baltic Sea in late 1939.
Although the North Atlantic 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 Atlantic.
details: (A) above page 25.
took only two weeks for Europe 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
(Kassel), with three cyclones on the periphery; one the off Lofoten
(970mb); one in the middle of the North Atlantic, south of Iceland
(980mb); and one off the coast of Porto/Portugal (1,010mb). The corridor
via the North Sea 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”.
from average? – September 1939 – First signs?
the first few days of September 1939 the weather in Western Europe was
influenced by a high pressure over Scandinavia. 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
Netherlands and then to Brussels 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 Iceland on
September 9th (1,005mb), Northwest off Scotland’s coast on
September 10th (1,005mb), moving via the Northern North Sea to
Jutland (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.
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 Iceland and Scotland from
September 16 – 28. Most significant comments of the Seewarte analyst are
September 1939; Cyclonic activities over the Polar Sea 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.
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 Europe. 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.:
October 1939; Along with a peripheral low, the first effective gust of
maritime air has reached Northern Germany. A continuous WWD, however,
cannot be expected yet.
October 1939; A broad high-pressure bridge has formed between the Atlantic
and Scandinavia 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 Russia, with low-pressure disturbances to the North and
South of it.
October 1939; Usual weather is changing now and the high pressure bridge
which links the Azores 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
Scotland remains, a further stream of cold air from the Nordic Sea area
(Nordmeerraum) is cut off.
of October 1939; Analysis of the weather chart for November 2reads as
lies in the South (Southern part) of the high-pressure area and mostly
experiences winds coming from East till North (NE- 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
This is a very strong and clear indication that huge air masses moved
towards the North Sea, 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.
1939 – Average not returned
for 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 Europe at about
the middle of the month.
November 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
–Southern Russia – and WWD-like turbulence activity in the North of
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.
November 1939; A very distinct west wind weather situation rules over
North and Middle Europe.
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 Atlantic to the Eastern
hemisphere. By 7th December 1939 a high pressure forms near
Aachen (West Germany/Belgium), stretching to Norway, 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.
December 1939; Quite distinct Atlantic frontal zone of the last few days
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.
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….
December 1939; A high pressure area that yesterday lay over the Northern
coast of Scotland, lies today over Central Germany with a central pressure
of 1,034 mb. The heavy fall in pressure over the Polar Sea area
(Nordmeerraum) has produced a low there.
this date the West Wind Drift was defiantly barred from entering Western
foregoing investigation stressed the significance of the observed change
of wind direction in Hamburg during October 1939. Wind direction had
dramatically changed from prevailing SW winds to dominating NE winds.
this stage it might be worth noting the research made by Drummond
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.
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.
December 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 Northern
Europe through a moderate winter. The coldest winter was due. (A) The war
at sea made the seas bend the weather in Northern Europe 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.
Broennimann et. al.
Bigg & Inque
Chen et. Al
Lukas & Webster
Broennimann et. al.