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Numbers in brackets refer to numbering on: 

A.     Introduction

 1    Scope and Aim         
 5    Prologue : Article from 1993 

 B.     Cooling of Europe 

7      Arctic Europe - winter of 1939/40 (2_11)          
23    West Wind lost - Europe cut off (2_12)          
37    War at sea 1939 -  Facts and events (2_13)          
45    Sea Mines September - December 1939 (2_14)          
59    Bombs and depth charges at sea (2_15)          
69    Cooling of North Sea - 1939 (2_16)          
87    Baltic Sea paved way for extreme winter (2_17)          
97    Cyclones and shells - War at sea events (2_21)          
107   Resultant Rain due to War - 1939 (2_31)          
117   USA winter weather 1939/40 caused by war 2_32)          
123   War in China  - 1939 (2_33)          
127   Russia invades Finland, December 1939 (2_41)          
141   Turkey Earth Quake - 27 December 1939 (2_51)          
149   Mediterranean - Strange weather - winter 1939/40 (2_52) 

C.     Three European winters: 1939 – 42 

153   Occupation of Norway - Return of Ice Age (3_11)          
173   Naval activities in Baltic Sea 1941 (3_21)            
181   Winter weather - Cold axis 1941/42 (3_22)          
193   Stockholm’s arctic winter of 1942 (3_23)          
199   Three year ice package, 1939-1942 (3_31)  

D.    Global sea war and climate changes 

211   Oceans in times of war: 1942 to 1945  (4_11)          
225   Ocean System affected (4_12)          
245   Extreme winter of 1946/47 in Europe (4_21)  

E.     Severe Warming 1918 

251   Europe Weather-Influence by WWI (5_11)
263   Spitsbergen heats up - Big Warming 1918 (5_12)
275   WWI warms up climate at Spitsbergen? (5_13)
285   Sea Mines Warfare 1914 - 1918 (5_14)
291   Warming of Europe, Greening of Greenland (5_15) 

F.      Climate changes twice 

303   Two wars at sea - Two climate shifts (6_11)          
311   Epilogue, Article from 1994          

G.  313   References   

Resultant Rain due to War – 1939 (2_31)

Aim of this paper

 How World War II  (WWII) drove Northern Europe into the hardest winter for one hundred years is subject of  a number of chapters. This paper aims to show and discuss that  not only Europe but  the whole northern hemispherefell prey to an arctic spell. United States and China experienced  severe cold inJanuary 1940, while Northern Europe was back in ice age conditions for the duration of two months.

 Whileconsidering  reasons for these occurrencesof ‘cold’ conditions in the winter of 1939/40 in Europe, it should not be ignored that military activities on land may have disrupted the balance in the atmosphere by ‘squeezing’ humidity out of the air. Obviously, less water in the air, means colder but dry air. A place where this could have happened was the Western Front between France and Germany after the start of WWII, where more than 2 million soldiers had been put in positions along this Front.

  It rained  double or even triple the quantity as against recorded long-term mean precipitation in areas which were within a fewhundred kilometres range of  this war front line. Some regional areas had only days of rain during October. Just few weeks later the USA experienced extremely dry air and alsorecorded low rain over the whole country. (A) In the end of December, winter set in andtook the entire Northern Hemisphere in its icy grip by early January 1940, and remained frozen throughout the month.

 Further details: (A) USA dried out, 2_32.

 Thispaper attempts to focus attentionon this ‘rain making’ phenomenon during the initial war months in 1939. Only at this stage of WWII did the war activities directly interfere with  common ‘nature and climate’. Thus this short period of time can be regarded as having gone through a direct ‘clash’ between common nature – in a statistical sense - and civilization. This can be compared with the sudden major eruption of a volcano with global implications. The time it took for the spread of volcanic  ash and dust  around the globe after the huge eruption of the volcano Krakatoa in Indonesia on August 27, 1883 until the end of the year may serve as an example[1]. In this case nature took charge and after a relativelyshort period of time, the atmosphere returned to ‘equilibrium’, making it difficult to prove the source and reasons for this specific meteorological event. It would assist in researches on climate changes, if the  impact of WWII - during the first few months – was under consideration, or when the war after having entered its 1st, 2nd or 3rd years has to be studied in detail. The German meteorologist R. Scherhag[2], observed a “great disruption incirculation” during thewinter of 1939/40 only, even though the winters that followed in 1940/41 and 1941/42 were also of similar nature. However, before the second and third  winters of the war, military activities took place throughout theyear, giving nature time to move from ‘equilibrium to equilibrium’ without a sudden disruption.  Althoughthis aspect is admittedly rather difficult to explain, one particularpractical example is part of this study. This example demonstrates a link between excessive rain in Central Europe (see this chapter), and the record ‘dry air’ in the United States from October to December 1939 (next chapter). This is a substantial evidence of anthropogenic influence. This proof, on a meteorologically sensitive issue, is presumably valid only when WWII had just started. Why didthe USA, after a ‘normal’ year, suddenly receive only very dry air for three months, while the war in Europe that ‘squeezed’ water out of the atmosphere only a few weeks earlier?

Before continuing it should be stressed once again, that the making of the arctic winter 1939/40 in Northern Europe is primarily a regional affair due to war at sea in adjacent waters. Making the atmosphere rain and pave way for arctic air should be regarded as a temporarily contributing factor only

Limitations of this paper

 This paper does not proposeto discuss physical/chemical processes in a hydro-dynamic environment. Itaims onlyto show that with the start of WWII certainevents occurred which cannot be relatedto conditions other than war activities. However, war activities in this respect can mean quite different thingsas mentioned below:

 1)       The war machinery and its activities penetratethe atmosphere directly or indirectly with physical/chemical means, which subsequently set processes in motion that eventually producerain; e.g. the raging of war along the Western Front and many otherbattle fields and the burning ofcities all over Poland during September 1939.

2)       The war machinery and its activities also  stirred  and mixed the seas and oceans, with the  following results:

a) acceleratedevaporation,

b) raised vapour and initiated flow of  air, from Northern Scandinavia or from Russia to the North and Baltic Sea; 

c) Presumably cold air (colder than seasonal average) forced humid air into increased precipitation, e.g. in Central Europe.

d) It started to ‘block’ the West Drift, commonly moving maritime air from the Atlantic through Western Europe, via the North Sea. Instead, continental air  flew infrom the east.

e) The continental air, colder than maritime air, thathad been coming via Scandinavia or the ‘corridor’ of the Southern Baltic Sea/Poland and North Germany along until it reached the North Sea, could have been a major contributor to the excessive rain along and behind the Western Front.

3)     The war in China was also a factor which should notbe ignored. However, very little material from the Far East had been availablefor this study which can at best help to attempt a basic assessment. Furthermore war in China, wouldhave had hardly any impact on the autumn weather in Europe. However, some relevance of this war on drought conditionsin the USA in late 1939 cannot be ruled out.

4)       The topics mentioned below will bediscussed in greater detail in chapters:

  • North Sea cooling (2_16), concerning items 2a-d;

  • Lost West Drift (2_12),concerning  items 2c-d;

  • War in China 1939 (2_33), concerning item 3;

  • USA dried out 1939 (2_32), concerning item 3.

The lack of rain during the German invasion of Poland in September 1939 will receive attention.  This attack which wasan extremely destructive military operation could possibly have derived Poland of ‘normal’ rain. If so, it could serve as a proof that military activities along the Western Front kept Poland rainless. It would be a sadly ironic event, if true (see below). The situation on Polish territory during September 1939may have also contributed to the blocked ‘West Drift’ in a minor way. 

 A final aspect, although speculative, should also be mentioned here. The military onslaught on Poland during September 1939 was, until then, the most massive military land war operation in  such a short period of time. It ended after four weeks, with Warsaw burning for many days. All the material that had been thrown into the atmosphere, like that of the burst of the Krakatoa 56 years earlier, could have served as ‘condensation nuclei’, if it had managed to travel a little fartherto the west, contributing to heavy rain along the Western Front, or influencing rain conditions further east, e.g. when Russian and Japanese forces waged a week long battle on the boarder between Outer Mongolia and Manchuku in August and September 1939. (A)

Further details: (A) War in China, 2_33.

Basic Factors

 Weather modification has been studied intensively by scientists since WWII. A number of programmes and experiments have been conducted[3]. There are actually quite a few theoriesas to which activities ofhumans may affect the natural causes of weather[4]. Anthropogenic aerosols can have an impact on the weather process. Rainmaking experiments have been performed on the assumption that some clouds precipitate inefficiently, or not at all, because they are deficient in natural nuclei. In some cases clouds only  needsome “seeding” to make them produce ice nuclei, snowflakes and raindrops. 

  • Rain processing: Water can condense in the air by the use of molecules as condensation nucleus. Condensation occurs on a wide variety of aerosol particlese.g. particles of dust, salt, desertsand or smoke. These particles when condensed, usually lead to cloud formation. Among the highly efficientcondensation nuclei are salt particles produced by the evaporation of sea water. But it now appears that particles produced by man-made fibresalso make a major contribution[5]

 The biggest rain making experiment may have started in the autumn of 1939. Since the 1st of September a lot of ‘seeds’ had been pushed into the air. It was possible for themto ‘make’ rain and this is precisely what happened. A several hundred kilometre long military defence zone between France and Germany, the Maginot Line and the Westwall, wereput into full operation immediately after the war had started. It began to rain significantly onthe continent along the Western Front. It rained more than the average in September, even more heavily in October and November and still morein December before Northern Europe was dragged into arctic weather conditions with frost, ice and snow until March 1940. Only the firstfour war months, viz. September to December 1939, are the subject for the following study as, latest by December 1939, European weather had lost its “natural texture.

 Meteorological data indicate that excessive rain was fed by “seeding” due to war. Rain fell within close distance of war activities in the West, while further East the Poles waited in vain for rain. 

 Although neither big battles nor “shoot outs” occurred along the huge defence system in the West, everything was done to improve defence capabilities and to prepare two million soldiers for the worst. Therefore bothfronts were busy day and night with transportation, construction, survey, training and military encounters. The first substantial clash saw 700 French tanks and planes moving seven miles over the Saarland border, while 300 air planes attacked German positions in the Aachen industrial region and munitions area, some 125 miles further north, (NYT, 7 Sept.1939), encounters that occurred since then frequently. At the same time British troops were landing on the continent rapidly, while German planes targeted England for the first time, (NYT, ditto) the  Royal Air force bombed the isle of Sylt. (NYT 9 Sept 39).  There were several encounterswhich occurred in numerous  placesalong the Western Front and elsewhere every day. 

Poland without rain in September 1939

 According to anassessment by the German meteorological service, September 1939 was considerably wet from the upper and middle of the Rhine region (Duisburg/Cologne to Frankfurt/Darmstadt) eastward to Silesia. Large parts of middle and southern Germany received double than average rain.  On 4th September, a wet warm high pressure front (1015 mb), approached from the Atlantic, which brought to the whole of West Germany mist and rain, but  movedquickly eastwards. The warm front was almost exactly in line with the French/German Westfront at 8:00 a.m. on Sept4th,  the with centre of a  low pressure close to Luxembourg and rain coming down in Germany, leaving nothing for Poland[6].

 On 11th September,a low pressure(1,000mb) originatedwest of Jutland,  moved south to the Schelde area (12th), and to Belgium (13th), bringing lots of rain to North Germany and excess rain of 50mm to 100mm to Southern Germany. This low-pressure cyclone moved through the North Sea, close to the sea mines that the German Navy had started to lay quickly, across the middle of the North Sea, at the outer edge of the German Bight. This could possibly be the first example of acyclone being“attracted” by sea war activities whichproduced “evaporation”. (A) At least the cyclone also gave Poland some rain before the 13th of September but it was too little, too late. 

Further details: (A) Cyclones and shells, 2_21

Areport (NYT, 15 Sep. 1939) that Warsaw received heavy rain, was proved  wrong.It was only a drizzle in most areas (NYT, 17 Sept. 1939). By then Warsaw was encircled. The Red Army marched into Poland from the East. Days of the Polish Republic were numbered. The Nazis had deployed5,000 planes in Poland (NYT, 25 Sept. 1939). On September 25, 1939, 240 German planes bombed Warsaw, dropping 560 tons ofbombs, including the first 1,000 kg bomb. Meanwhile 1,000 batteries shelled the city. 30 transport aircraft dropped 70 tons of fire-bombs. Warsaw was on fire for many days. Poland surrendered. There was nothing butdust and ashes from burning citieseastward around for a couple of days or weeks.  Did thisdust help topour horrendous rain on New York in early November 1939, recording 1.4  inches in one day? (NYT, 6 November 1939). But some of the dust could also havebeen moved by easterly winds to the Western Front contributing to excessive rain in Central Europe.

The German Meteorological Service  makes the following assessment for September 1939: Precipitation in North Germany is markedly below the mean averages. The opposite occurred in all other parts of Germany, with significantly higher quantity of rain than mean averages. The September 1939precipitation in percentage termsof average figures (1851-1930) for some places in Germany had been as follows: 

Berlin-Dahlem (197 %); Frankfurt/Oder (197 %); Breslau (204 %); Ratibor (210 %); Karlsruhe i.B. (208 %); Stuttgart (199 %); Ulm (226%); Wuerzburg  (215 %); Muenchen (212%)[7]. 

October 1939– Raining ‘Cats and Dogs’

 In the West, Middle and South Germany volumes of rain recordedat most observation stationswas more than double, in some cases even 3.5 times more than usual, as follows: Augsburg 366%; Noerdlingen 362%, Kaiserslautern 336 %, Wuerzburg 316 %[8]

Due to the war situation there is hardly any weather related  documentation available.  With respect to Darmstadt it was reported that it would be necessary to go back to the year 1882 to find a similar volume of precipitation during a period ofthree months, i.e. Sept.-Nov., asthe autumn had never been so wet since more than 100 years[9]. The nearby city of Frankfurt a. M. recorded: 137%, 265%, 237% during the time in question.

 The Black Forest and Freiburg i. Br. recorded 30 days of rain; a number of other locations had up to 24 days of rain[10].

 An eye-witness report may serve to illustrate the special situation at the Western Front. According to the New York Times, by mid October the West Front saw a ‘Nazi Attack with 100,000 men’ and the following weather:

 “Bad weather prevailed today on the entire Western Front, where conditions could not have been worse for offensive operations. The Germans were obliged to use railroads for  amassing/transportingreinforcements, with the result that all lines of communications were clogged throughout the day. Rain and fog kept allied planes grounded.

 French artillery whipped the German front line positions, roads and railroads with shrapnel to hamper  operations.

 Rains aidedflood in Rhineand forced evacuation of several Westwall blockhouses opposite Strasbourg. They also caused the Moselle to rise to a level eleven feet above  previousweek’s level. The Blies and other small streams flowing into the Saar River were flooded and the terrain alreadybadly pocked by artillery firesin Monday’s bitter fighting, was covered with water holes”. (NYT, 18 Oct. 1939). 

Southeast England recorded rainfall of more than three times above average inOctober 1939. Greenwich saw a higher rainfall only in 1888, and before that in 1840[11].  Greenwich total for October (6.16 in.) and November (4.13 in.) together –10.29 inches – was the highest ever since recordinghad begun at Greenwich[12]. Similar conditions had been observed at Camden Square (London), where hours of rainfall are recorded as follows: October 77.3 h.,  November 96.7 h. These were  50 hours higher than the average[13].

 Holland also reported  rainsthroughout the month ofOctober 1939. (NYT, 2 Nov. 1939). Similar conditionpresumably prevailed in Belgium and Northern France as well. In January 1940  NYT correspondent G. H. Archambault reported while staying with the French Armies: ”the autumn of 1939 was one of the wettest known”. (NYT, 26 Jan. 1940).

November 1939 – Rain Spares France – At least for now

 “Germans continued to shell Forbach. Artillery hammered as  forcefullyas wet weather impeded action by infantry”, (NYT, 06 Nov. 1939). Another headline of the NYT (16 Oct. 1939) reads: “French Still Wait for Reich’s Attack – Rain Impedes Fighting”.

On 19th October plan “Yellow” for the invasion of France was finalised. On 7th November commencement of the invasionplan was postponed for the first time. A Blitzkrieg was not advisable with ‘General Mud’ in company. Hitler wanted to go aheadand would have sent the Wehrmacht across the boarders in late 1939, but for excessively wet autumn weather conditionsmade even Hitler think twice.

Indeed,  November 1939 weather conditions were not much better than in October. In general it was a bit too warm and too wet, 200% and moreof normal for the season, inHannover, Aachen, Kassel, Frankfurt a. M., Magdeburg, Ulm, Wuerzburg.

By November 19/20, 1939; The Rhine had been rising again and there was  heavy flooding in Switzerland.. (NZZ, 20 Nov. 1939); Heaviest flooding of rivers in Belgium and Holland made  navigation impossible. Further rise of water was expected. (NZZ, 29 Nov. 1939)

 That the quantity of rain in East-South-East of Central Europe in late autumn of 1939 was excessive, was confirmed by a NYT report  inmid December: “The waters of the Danube River has begun to recede from the record December flood level, and the speed of current, caused by swollen tributaries, relaxed.” (NYT, 13 Dec. 1939).

Saxony and  Switzerland - December 1939

 Nothingremains to be said on the rain making issueinthis chapter. Saxony with itscapital Dresden had similarautumn rains as in other parts ofGermany. Snowfallin Finland, close to Russian-Finland war theatre, since end of November is certainly a factor which should not be ignored.  See: next section.

In Saxony, Dresden reported heavy snowfall lasting 36 hours on December 6 and 7, corresponding to 50 litres per square-metre, with a decrease intemperatures to minus 7°C. Some thing similar had happened 57 years before, in 1882[14].

Switzerland alsoexperienced a very wet autumn as well, with heavy flooding in late November, and saw last rain on December 11. However, Zürich experienced only some drizzlein early January 1940. (NZZ, 14 January 1940). 

Russian-Finnish battles in December

 War  insidethe arctic circle is a serious matter in terms of weather making, especiallyif the fighting starts at the meteorologically most sensitive time, i.e., from the end of November and  till the end of  December.

Fewweather indications from early December may serve as anillustration (NYT):

Dec. 03: Bad flight weather; Mist and rain on Friday; Snow falling in Helsinki yesterday.

Dec. 04: Blinding snowstorm aids defence; North of Ladoga Lake ice is still thin; Petsamo: bitter cold and  severesnowstorm.

Dec. 05: Snowstorm hinders foe; snow is pileddeep at various sections of the battle line; early setting in of winterconditions; Helsinki feels safer in snow storm; snowstorm slowed down activities on both fronts and air. 

Weather conditions turned worse and worse. The Red Army was completely unprepared for this early winter onslaught by nature and suffered heavy losses in terms of men and material. (A) 

Further details: (A) Russian-Finnish war, 2_41.

 With regard to ‘rain making’, the Russian – Finnish winter war during December 1939 should certainly not be ignored in an overall assessment on the driving ‘hydrodynamic’ forces leading to thesewinter conditions. Shelling and bombing wouldcertainly have contributed to heavy snow and snowstorm conditions, and precipitation that would otherwise have gone down further east somewhere before or behind Moscow. 


 The suddenness and extreme of the war winter of1939/40 had been such an extraordinary meteorological event that everyaspect relating toits rapid build up should be elaborated and weighed. The  atmosphere during the particularly climatically sensitive autumn months of September to December in the Northern Hemisphere reacted immediately. Rain thatcame down in Western Europe as heavy downpoursince the war had started on September 1st had not been available in the USA during the corresponding period. While mostly excessive rain occurred in Europe in October, four weeks later the USA experienced a record dry month with only 44% precipitation of average for the whole country during November 1939

 What followed the ‘ humidity gap in the air’ was,  inter alia, a ‘disruption incirculation’ all over the Northern Hemisphere. Excessive rain in Europe and dryness in the USA were certainly not the only causes for this ‘disruption’.Temporary ‘absenceof water’ in the atmosphere provides a perfect explanation as towhy not only Europe fell prey to an ice age winter, but also China and the USA had suddenly experienceda very severe January 1940. In fact, cyclonic activities are weakened by less water in the air.      

 This study aims to highlight that actual “rain forcing” in autumn 1939 might have contributed to free the pathfor masses of arctic air to move deep south with little resistancefrom maritime air in all northern parts of the Northern Hemisphere. The severe winter, the coldest for one hundred years in countries bordering most war-affected seas in Northern Europe, did not  come‘just out of the blue.’ The clue to thisis to be found in the war at sea. The distant impact of the war in Europe and in the winter ofJanuary 1940 in the USA and China had presumably contributed to‘rain forcing’ in Europe that evidently brought a record dry autumn spellto the States, and subsequently paved the way for arctic air to dominate over areas usually under the influence of the West Drift. In this respect it is worth noting that East Siberia and Canada had been actually too warm (about + 7°C) at the same period of time[15]. Aninteresting aspect, whileassessing events in late 1939, is that nature was still in its ‘pristinestatus’, allowing observations or deviation to be assessed on an uninterrupted or ‘mixed-up’ data basis. The autumn 1939 provides a very important period in this respect.

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G. References

1 Wexler, Spread 
 2 Scherhag, 1951
3 Sewell  
 4 Parker, pp 541-547. 
5 Parker, p.100 
6 Seewarte 
8 Witterungsbericht 
 9 Fischer, Nasser 
10 Witterungsbericht 
11 Lewis 
 12 Correspondence, Greenwich    
 13 Correspondence, Camden
14Naegler, Schneefall
15 Scherhag, 1951