Chapter B. Arctic winter 1939/40
Part I

Autor: Dr. Arnd Bernaerts (date of publication 2006)
NOTE: All book images replaced
Published by: iuniverse/USA

 General winter weather scenario

 The severe winter period lasted from mid-December 1939 until March 1940. Even in Northern Spain, temperatures of minus 18 C were recorded, while in France people began to wonder whether they lived in Western Europe or in Siberia. However, the cold centre was situated in the Netherlands and in Northern Germany, and up to the Baltic countries. The low temperatures were generated by the arctic air coming from Siberia. Extreme weather conditions were felt in Finland, Sweden, Southern Norway, Denmark, South-western England, Northern France, Germany, Hungary, Yugoslavia, Romania, Poland, the Baltic countries, and Western Russia. In Southern Europe, south of the Alps, weather was extremely cold and unpredictable for some days, but average temperatures did not deviate significantly.

 By mid-January 1940, newspapers reported extreme temperatures for Northern Europe: –48°C in Finland and the Baltic countries, –35°C in Southern Sweden, –26°C in Denmark, –40°C in Poland, -32°C in Budapest, –20°C in Paris. The weather remained extremely cold until April 1940.

 By mid-February, a second cold wave took hold of Northern Europe with temperatures of -25°C in Sweden, Denmark and Holland, -33°C in Budapest, and -47°C in the Baltic countries. Sub-zero temperatures lasted in Potsdam/Berlin until the 15th of April, with only 20 days without freezing temperatures during the whole winter period.

Winter conditions in Northern European Countries

 A brief overview of newspaper reports may give us some information about what it meant for Northern Europe to be thrown back in the Little Ice Age.

 South-eastern England: At Kew Observatory, January 1940 was the coldest month since 1791, with the highest percentage of frost days. Greenwich figure was also the lowest recorded during the past one hundred years. In the close vicinity of London, the river Thames had frozen for the first time since 1814 (Neue Zürcher Zeitung, the 29^th of January 1940).

 The Netherlands: As early as the 6^th of January 1940, drift ice in the East of Scheldt was so severe that Ameland was temporarily cut off from the mainland. Freezing conditions went on. By mid-February, hundreds of persons abandoned their homes because of the threat of c

rushing ice packs boiling up from ice-locked canals, rivers and seas. In mid-February, Amsterdam Weather Bureaus reported the lowest temperature ever recorded in the Netherlands: 11.2 degrees below zero Fahrenheit (-24°C). Water transportation in the Netherlands was completely paralysed. Canals were covered with thick ice for more than six weeks, while traffic on the Rhine and Waal had already stopped in early January.

 Denmark: Even before the end of 1939, snowstorms swept Denmark. In mid-January 1940, Copenhagen registered -26°C (-15°F) and there was no sign that the cold wave would come to an end very soon. Heavy snowstorms blocked or slowed down the traffic in many parts of Denmark. “It is Denmark’s worst winter since 1860”, the New York Times reported in February 1940.

 Sweden: On the 21^st of February 1940, the New York Times reported: “In Sweden all cold records were broken in the last twenty-four hours, the coldest since 1805”. Analysing the data base recordings for those four months i.e. December 1939–March 1940, the winter 1939/40 proved to be the coldest since 1880/81.

 Finland: On the 24^th of December 1939, James Aldridge’s report (extract from NYT, the 25^th of December 1939) was saying: “The cold numbs the brain in this Arctic hell, snow sweeps over the darkened wastes, the winds howl and the temperature is 30 degrees below zero Fahrenheit (minus 34.4°C). Here the Russians and Finns are battling in blinding snowstorms for possession of ice-covered forests… I reached the spot just after the battle ended. It was the most horrible sight I had ever seen. As if the men had been suddenly turned to wax, there were two or three thousand Russians and a few Finns, all frozen in fighting attitudes. Some were locked together, their bayonets within each other’s bodies; some were frozen in half-standing positions; some were crouching with their arms crooked, holding the hand grenades they were throwing; some were lying with their rifles shouldered, their legs apart… Their fear was registered on the frozen faces. Their bodies were like statues of men throwing all their muscles and strength into some work, but their faces recorded something between bewilderment and horror.”

The Baltic Countries: Already in December 1939, in the Eastern parts of the Baltic countries (at the Russian West border), the temperatures fell to -17°C (between the 24^th and the 25^th of December), and below -20°C one day later, extending to the Baltic coast and recording -14°C in Klaipeda and -17°C in Gdynia (Bight) on the 27^th of December[i]. The harshest cold wave in years reached the Baltic countries by mid-January 1940, with temperatures of 40 degrees below zero Fahrenheit. In mid-February 1940, more than 10,000 persons were still suffering from severe frostbite in Estonia, Latvia and Lithuania. At least five persons froze to death in these three Baltic countries, where temperatures reached 54 degrees below zero Fahrenheit (-47.7°C) for the first time in 160 years and where the Baltic Sea froze over.

 In Central Europe, in countries like Hungary or Romania, a very severe snowstorm paralysed shipping in the Black Sea and the lower Danube River even before Christmas 1939. On the coast, temperatures dropped to 15°C below zero. Snow also fell all over Bulgaria on the 21^st-22^nd of December, this way starting a new cold weather episode (down to -16°C). Temperatures of -20°C were recorded in Northern Bulgaria. During the remaining days of 1939, ice blocked the Danube and prevented German supplies from getting through. Railway traffic was expected to be hampered by snow, too. On the 30^th of December 1939, The New York Times reported: “Cold winds have been recently blowing westward from Russia.”

 In January 1940, weather throughout Eastern Europe was unpredictable: very cold, very snowy and possibly the coldest in fifty or even more years.

 In mid-January 1940, temperatures dropped at 40 degrees below zero Fahrenheit in Romania, while Bulgaria was reported to be suffering under the worst cold people could remember.

 February 1940 was by no means better. It was reported that all records of cold weather in Europe were broken during that month and just when people were hoping that the worst was over, another cold wave hit the entire continent. Budapest endured the harshest cold weather in sixty years: 28 degrees below zero Fahrenheit (-33°C).

 Extended areas of Germany, particularly those close to the North and Baltic Seas, experienced the coldest winter in more than 100 years. The centre of the cold wave expanded from Amsterdam, via Bremen, Hamburg, Berlin to Königsberg (Kaliningrad). In the Helgoland Bight and Southern Baltic Sea, naval activities were at their peak: starting with a 10 days battle from sea to shore, and from shore to sea, in Gdansk area in early September, and continuing with the laying of many dozens of mine fields along the German coast. A detailed description will be provided later.

 Hamburg, a port city on the Elbe River, close to North and Baltic Seas, experienced record weather conditions despite its usually maritime climate, with winter temperature averages just above zero degrees Celsius. Instead of that, average temperature was below minus 12°C for almost two months (the 1^st of January–the 20^th of February). The Elbe was under ice. When unusual freezing started in December 1939, a big headline of a Hamburger newspaper was saying: “The Elbe will never be frozen over, since 1874/75 icebreaker would keep the shipping fairway open”. After a while, nature proved that assertion wrong. The German navy encountered many difficulties. Many naval vessels were stuck in the middle of the floating ice.

For Berlin, Dresden and Halle this was the coldest winter in 110 years, and the summary of the daily data between November 1939 and March 1940 proves it beyond any doubt. After 1829/30, no other winters have been as cold as winter 1939/40 was. The coldest months of January in Berlin since recording started, in 1719, are: 1823, 1838, and 1940.

 At the most eastern end of the southern region of the Baltic Sea, former Königsberg (later Kaliningrad), whose usually winter temperatures were of an average of –2°C, had to cope with the following average temperatures, as shown in the graph.

 Summary: The evidence of the extraordinary winter conditions is overwhelming. It is further possible to clearly demonstrate that the entire Northern Europe, from Helsinki to Sofia and to London, fell prey to arctic conditions, while in a number of cities, like London, Amsterdam, Hamburg, Berlin, Dresden and Kaliningrad (Königsberg), there were registered record low temperatures, which were not experienced in more than a century before. As we have offered an overview of the impact and the characteristics of winter 1939/40, our next step is to explain and establish how this could happen. After all, global and regional weather is based on physics and nothing happens without a cause.

 Seas churned by navies

 Laws of physics governing Hot Soup in a Cup

 Laws of physics also apply to hot soup in a cup. WWII unleashed tremendous military forces unheard-of in history before. Millions of soldiers marched up and down battlefronts. Thousands of naval ships ploughed oceans and seas day and night. In autumn 1939, the most affected seas were the Baltic- and the North Sea. Normally, both of them would have stored heat to their highest capacity by the end of August. Since the last Ice Age, they served in autumn as a substantial heat reservoir for the forthcoming winter season when days are short and sunrays contribution to regional weather conditions is unobservable. Together with the Gulf Current from the west of Great Britain and Norway, these seas ensure moderate winters to Northern Europe. These seas determine the weather of Western Europe (in the north of the Alps): maritime or continental winter climate. Winter 1939/40 in Northern Europe turned out to be an extremely continental one.

 Allowing navies to participate in a war at sea, in Northern Europe natural heat reservoir, is like hastily stirring a hot soup to cool it down for quick consumption. Once the soup in a bowl is cooled down, it will never warm up naturally again. Likewise, once the heat storage of Northern- and Baltic Seas has been diminished, water will warm again only during the next year summer. And as navies were out on the sea in autumn 1939, the inevitable happened. Arctic cold wave was due to come in the winter 1939/40. Naval activities during the first four war months (from September until December 1939) represented an important force and the laws of physics didn’t remain unnoticed.

 “A spoon in a cup”

Dimension does matter if one considers the effect of stirring the soup in a bowl with a spoon. In oceanic terms, the enclosed seas of Northern Europe represent only 0.2% of global sea surface and a mere drop with respect to the total volume of the seas around the world (0.0026%). Nevertheless, they play a crucial role as their size represents roughly one-third of North-western Europe. As for the effect of the ‘turning about’ of the sea areas, their depths are of considerable importance. In the North and Baltic Seas, depth is not an impressive figure i.e. an average of mere 50 meters. In comparison, Mediterranean Sea has an average depth of 1,500 metres and sunrays warm the sea even in wintertime. Battleships in those days had an average size of about 35,000 tons, a draught of 10 metres and a speed of 32 knots (approx. 60 km/h). Battleships accompanied by a number of escort destroyers across the seas turned huge water areas around. Suddenly, there were thousands of naval ships out on sea, hunting enemies or being hunted from shore, air, surface ships or submarines.

 Naval Fleets

 By December 1939, the number of main naval ships belonging to Germany, Great Britain, France, Italy, the Soviet Union and Italy amounted to more than 1,000 vessels (including submarines, torpedo boats, etc.), with a total tonnage of 2.8 million plus at least another thousand smaller vessels and boats serving as mines sweepers, etc.

 Great Britain: 250 big naval vessels (183 destroyers and bigger vessels) and approx. 57 submarines;

Germany: 30 big naval vessels (21 destroyers and bigger vessels) and 57 U-boats.

 Remember that these figures indicate the navies’ size on the 1^st of September 1939, because thereafter new naval ships came into service almost every day.

 The Merchant Fleet and the Convoy System

 At the beginning of the war, world merchant fleet counted 30,000 ships with a total tonnage of about 70 million. British fleet was by far the largest with 20 Million tons, followed by Norway with 5 Million tons, Germany with 4.5 million tons, and France, the Netherlands and Italy with about 3 Million tons each.

 As far as Britain was concerned, shipping activity was of utmost importance, so no effort was spared in order to maintain this. Atlantic supremacy should ensure sufficient supply to Great Britain at any time. Allies introduced the convoy system without delay, this strategic display having been very successful during WWI. The convoy system was supported by the First Lord of the Admiralty Winston Churchill who once said that it was “the dominating factor all throughout the war… Battles might be won or lost, enterprises might succeed or miscarry, territories might be gained or quitted, but dominating all our power to carry on the war, or even to keep ourselves alive lay our mastery of the ocean routes and the free approach and entry to our ports”6.

 Convoying meant that up to 50 ships sailed in a display of four to five columns, frequently altering course by up to 90 degrees simultaneously (zigzagging), while naval escort vessels formed a shield around them. The threat of submarines and raiders was imminent everywhere. Britain announced that it would arm 2,000 merchant ships with guns. In 12 months 3,000 vessels were armed with a 4.7-inch gun each. By December 1939, 5,756 ships had sailed in convoys, which mean that more than 1000 convoys have been organized in a short period of time.

 Submarine – U-boats

At the beginning of the war, German and British Navies had 57 submarines each. Britain eventually employed 270, the Germans about 1,000 during WWII.

 British submarines had the difficult task of intercepting well protected German shipping around Northern Europe by direct torpedo attacks or by mine laying missions. Although Britain never managed to operate in the Baltic Sea during WWII, Royal Navy submarines took its heavy toll of German troop transporters, supply ships and escort vessels, quickly forcing the Germans to adopt the system of defensive convoys when operating in the North Sea or, since 1940, in the Norwegian waters. During the Second World War, British submarines were credited with the sinking of 475 merchant ships, 105 warships and 36 submarines, and with the damaging of many others.

 What happened to submarines in North Sea and elsewhere for five years, day by day, since the 1^st of September 1939 may be illustrated by a news report headlined: ”British Submarines’ Crew, Bombed All Day At Bottom of Sea, Passes Time by Betting” (The New York Times, 6 October 1939): “the Admiralty today released a story about the crew of a trapped, crippled British submarine who ran a penny sweepstake pool at the bottom of the North Sea while the Germans groped for them with sweep wires and shattered bo

 

mbs and depth charges for twenty-four hours. In the first hour six depth charges sounded faintly and in the second hour the explosions, louder and nearer, averaged one every two minutes”. Another report of the same date states: “British destroyer patrolling northeast of the English Channel had trapped two German submarines early this week and forced them into a mine field where they exploded and sank”.

 However, submarine warfare during WWII actually meant success and failure to German U-boats in North Sea and North Atlantic, strategic areas for Great Britain’s vital supplies coming from Canada, USA, and the Southern Hemisphere countries. About a dozen German U-boats were already in the Atlantic when the war started in September 1939. Others operated in the European waters. In September 1939, groups of three to five naval vessels of the Royal Navy were formed to patrol large sea areas. These groups criss-crossed the seas day and night searching for U-boats and dropping depth charges when a U-boat was detected or assumed to be around.

 On the 14^th of September 1939, U-39 operating in the Hebrides area shot its torpedo at the 22,000-ton aircraft carrier ‘Ark Royal’, but missed. Escorting destroyers Faulkner, Foxhound and Firedrake depth-charged U-39 in a series of attacks reported by an eye witness as it follows: “We gained ASDIC Contact with the Sub and each ship in turn, went in at full speed and fired a pattern of depth-charges. Firedrake attacked last, as we came out of it and heard our depth charges explode, we thought we had missed, until up it came, vertical like a huge cigar and then flopped down slowly”. U-39 surfaced briefly, and then sank. A few days later, the attack of U-29 succeeded. In the early evening of the 17^th of September 1939, 22,000-ton British aircraft carrier ‘Courageous’ was on an enemy hunt together with four destroyers, in the Southwest areas (Southwest of Ireland), 150 nautical miles WSW of Mizen Head, Ireland. The carrier could travel at a speed of 30.5 knots (56 km/h). But the days of HMS ‘Courageous’ were numbered. “A German submarine struck a telling blow at the British Navy last night by sinking the 22,000-ton aircraft carrier Courageous, with loss of an unknown number of its complement of 1,100 officers and men. It was the first real success scored by the German Navy in this war.” From a salvo of three torpedoes, two hit the Courageous on portside. The destruction was devastating as described by Sub-Lieutenant Charles Lamb: ‘There were two explosions, the like of which I had never imagined possible. As if the core of the earth exploded and the universe split from pole to pole, it could sound no worse… In the sudden deathly silence which followed, I knew the ship had died.’ The Courageous turned over and sank in fifteen minutes, with a loss of 519 men who formed its crew. Lieutenant Wesmacott ‘heard two violent explosions which seemed to lift the ship’.

 Depth Charges

 This section is about ASW, namely anti-submarine-warfare. A depth charge is a ‘drum’ containing explosives with a fuse which is detonated at a preset depth and which is based on hydrostatic pressure. Developed in 1916, during WWI, a depth charge could detonate up to 100m depth and carried 150 kg of explosives. There was little development for this weapon between the wars except for a 300kg variant. At the start of WWII, depth charges were essentially the same weapon as it existed at the end of WWI. This situation changed quickly.

 In September 1939, The New York Times wrote about the procedures of U-boat hunting: “Once a submarine is located, British naval plans, so far as they were known before the war, call for attack by familiar methods of an enclosing diamond pattern of depth bombs, supplemented, of course, by shell fire and ramming if the submarine could be forced to the surface. In the diamond-pattern attack, the destroyer goes at full speed to the spot where the submarine, slow and clumsy under water, is thought to be. One depth bomb is charged just before the spot is reached. A few seconds’ later two more are lobbed out by a Y-gun so that they land out on eith

 

er side of the destroyer’s wake. In the front part of the diamond pattern, another depth bomb is dropped over the stern, some distance ahead of where the Y-gun fired. This way a large area of the sea is covered by this diamond pattern. The effect is further increased by the fact that the bombs are timed to go off at different levels, so that the area is covered not only horizontally but vertically as well. The bursting area of a modern depth bomb is considerable”.

 Evaluating the intensity of the destruction caused by the explosion of depth charges from sea surface to sea bottom is not easy. Many naval vessels were not out on sea for combat reasons, but for training, surveillance or testing, etc. For many commanders the situation was new and they took precautions against imminent or assumed threats, as the following report illustrates it: “Russian commanders of the transport ships and torpedo boats were so much afraid of being attacked by a Finnish submarine in the Gulf of Finland that they set off depth charges every 15 minutes or whenever an unconfirmed sighting of a periscope was reported, all that resulting in a total of 400 depth charges having been dropped by the end of the operation that day”.

 On the 29^th of November 1939, at dawn, U-35 was cruising east of the Shetland Islands, in the North Sea. At the sight of the British Destroyer ‘Icarus’, the U-boat crash-dived to 70 m depth and started steering evasive courses. As ‘Icarus’ electronic devices for U-boat localisation were out of order, depth charges set for 80m were dropped in order to feign an attack. Two nearby destroyers were alerted. After contact had been established, two more depth-charge attacks followed, jamming U-35 diving plans and placing it at a sharp up angle. Crew was sent to the ship’s bow to bring it back on even keel, but all their efforts were in vain. Explosions had also destroyed the fuel and ballast tanks aft. U-35 appeared suddenly at the surface and the crew was ordered to abandon the ship, but they were rescued by their attackers.

 During the first sixteen months of war, an estimated number of 33 U-boats were destroyed in about 4,000 depth charge attacks. Each attack could

 

mean the use of a few or, from the contrary, of many dozens of depth charges. The total number of depth charges dropped per month could easily reach several thousands. German naval vessels hunted Royal Navy submarines, too. Up to 10,000 or even more depth charge explosions could have occurred below the sea surface during the first four months of the war.

 Since then, development of depth charges focused on increasing the depth at which a submarine might be successfully attacked, due to improvements to their sinking speed. Since 1943, the detonation of depth charges carrying a charge of 100 kg of TNT at a depth of 300 meters became possible.

 Aerial bombing at sea

 Neither the German navy nor the British one had a fully operational aerial arm at the beginning of WWII. The German Navy never got one. British Royal Air Force Coastal Command became operational in 1940. However, airplanes charged with bombing missions were operating frequently (British airplanes in the Helgoland Bight and German airplanes on England’s East coast) or were attacking the enemy in the open sea. On the 3^rd of September 1939, Britain was in possession of a fully operational unit of 2,600 aircrafts; th

e Germans had nothing less.

 A few out of many hundred events are listed below in order to offer you an outline of what happened during the first few months of the WWII.

•  The 4^th of September 1939: The First RAF raid of about 30 planes. Organised in separated groups, they targeted a fleet of Nazi naval vessels in the German Bight. About seven RAF planes were lost in mission.

•  The 27^th of September 1939: In the middle of the North Sea, a squadron of British capital ships together with an aircraft carrier, a cruiser and destroyers were attacked by about twenty German aircrafts. Fourteen German land bombers made the attack.

•  The 29^th of September 1939: British planes attacked a German naval squadron near Helgoland. Five out of 11 Hampdens (bomber planes) are shot down by German fighters.

•  The 9^th of October 1939: British cruisers hunting submarines in the North Sea (southern coast of Norway) fought off German bombers, which attacked repeatedly. The Germans sent almost 150 planes to the scene of the battle.

•  The 17^th of October 1939: Nazis bombed the naval base from the Firth of Forth near Rosyth, Scotland. Three ships were damaged; two bombers were shot down and crashed in flames into the sea.

•  The 21^st of October 1939: Fighter planes shot down four German bombers out of nine which were deputed to attack a British convoy off the Humber estuary.

• The 5^th of November 1939: “Our outlook shouted, ‘Planes right ahead, Sir; three planes; they are diving, Sir’. Our foremost guns opened fire with a roar that drowned everything. The muzzles were elevated almost level with the bridge and yellow flames sprang out, obliterating the shapes of the German machines swooping over the convoy. The sea leapt up in columns where their bombs were dropped.”

•  The 14^th of December 1939: Twelve RAF bombers attacked German warships in Helgoland Bight, but ended up by losing between six and ten bombers.

•  The 17^th of December 1939: German bomber planes attacked trawlers near the English east coast and sank 10 boats of approx. 3,000 tons.

• The 19^th of December 1939: An air battle of significant proportions occurred the moment when British bombers encountered the German pursuit ships in the Helgoland Bight area. The loss was of 12 planes out of 24 RAF Wellington bombers deployed.

•  The 21^st of December 1939: “German aircrafts attacked thirty-five vessels, including two neutral ships during the last three days. Of the ships attacked, one coasting steamer and six fishing trawlers sank.”

 Sea mines

Between 100,000 and 200,000 sea mines have been laid during the few autumn months of 1939. Most of the mines were placed in the North Sea and a substantial number in the Baltic Sea.

East Coast Barrier

The British successfully mined their East coast from Dover to Orkneys during the first few months of the war. In September 1939 alone, the British minelayers Adventure and Plover laid 3,000 mines across the Strait of Dover. In the second half of September, the barrage was completed with 3,636 U-boat mines, which soon paid results, Germany losing three U-boats in October. The British set up the East Coast Barrier, a mine barrage between twenty and fifty miles wide, from Scotland to the Thames, leaving a narrow space for navigation between the barrage and the coast. In early January 1940 The New York Times reported: “British naval vessels are sowing some of the last mines needed to complete Great Britain’s 30,000,000-pounds protective shield for east-coast shipping, which is the most extensive mine field ever laid.” If one assumes that the weight of those mines varied between 300 and 1,200 pounds, the number of mines laid in autumn along the east coast alone would be between 25,000 and 100,000 mines.

The report of a mining mission in mid-October 1939: The German destroyers ‘Galster’, ‘Eckholdt’, ‘Lüdemann’, ‘Roeder’, ‘Künne’ and ‘Heidkamp’ took on their cargo of 60 mines each (except ‘Heidkamp’) at Wilhelmshaven, and departed at noon, racing northwards first, at 30 knots, as a misleading measure, then, at dusk, turning westwards for the target area: the mouth of the Humber. In the early hours of the 18^th of October, the five destroyers began their task, between the Humber Estuary and the Withernsea Light. On completion, the destroyers headed home at full speed. This minefield of 300 mines eventually sank seven ships.

Helgoland Bight (Deutsche Bucht)

 At the beginning of the war, the German Navy laid a large mine field starting from the Nethelands’ coastal waters (near Terschelling island) and going northwards across the Helgoland Bight up to the entrance of the Skagerrak, at a distance between 50 and 100 km off the coast of Schleswig-Holstein and Denmark. This barrage was known under the name of “Westwall”. For about three weeks, a flotilla of at least 25 naval vessels was engaged in laying mines along this “Westwall”.

The number of mines laid during the period in question could be somewhere between 20,000 and 200,000. But as the distance from Terschelling to 56° 30’ North is of about 350 kilometres (170 sea miles) and the 25 naval vessels charged with this task were able to lay thousands of mines per day, it seems reasonable to assume that, by the end of the year, the Reichsmarine could have placed somewhere between 50,000 and 100,000 mines.

Home Fleet’s surface vessels undertook a number of missions as well, with the purpose of laying mines in the German home waters. Such an illustrating example would be the mission undertaken by the British destroyers Esk and Express, which laid mines where “Westwall” ‘exit channels’ were assumed to be (in mid-September).

 Mining the Baltic Sea – 1939

War had just started when the 1,555-ton, Greek ship Kosti hit a German mine, two miles south of Falsterbo/Sweden, on the 4th of September, and sank after a terrible explosion in the minefield in the south of the Great Belt and the west of the Danish island of Zealand. Danish Government made public its plans of planting mines in its own waters. From the very first days of the war, the Germans had laid about 1,000 mines at the entrance in the Danish waters and they continued to lay mines during autumn as well. In the early November, gales had loosened several hundred mines from the German mine field, drifting them off the Copenhagen shore, where some of them exploded, breaking windows and frightening citizens with the terrific noise of their detonations.

During six long years, the situation got worse day-by-day. It is difficult to verify and tell the exact number of mines the Germans planted in the Southern Baltic Sea. Many thousands of mines were also placed in the Western Baltic Sea before the winter of 1939/40, and, as a result, the German Baltic waters suffered the impact of a compact ice cover starting with January 1940.

Other riparian countries planted mines as well. The Soviet Navy started laying mines in the Gulf of Finland in late September. An important number of mining activities of the Germans, Finns and Russians took place in this sea area during November and December 1939. The total number of mines laid in various parts of the Baltic Sea during the late 1939 could have been of several thousands.

Minesweeping

Minesweeping activities were another particularly effective means of churning and turning huge sea areas day-by-day, since the war started. A standard mine was the moored contact mine, a buoyant material filled with up to 1,000 kg of explosive. To avoid detonation, special ships used distant means to cut the mooring chain or wire attached to the mines to keep them afloat. Sometimes, the mines exploded before reaching the surface and if they surfaced they were blown up with rifle shots.

In November 1939, magnetic mines entered the scene. They could only be destroyed through forced explosion. From the climatic point of view, this was the worst case scenario. The mine was exploding in its location, at a depth of 20 or 50 metres, producing the biggest possible “stirring” effect in the water column reaching above. The countermeasure was to deactivate the ship’s ‘magnetism’ so that it could pass near the mine without activating it.

Minesweeping proved to be a tremendous, round-the-clock operation which implied covering millions and millions of sea miles in order to detect and destroy the ‘in waiting weaponry’. The efforts made during WWII were of huge proportions. German Defence machinery against Allied mining operations involved 46,000 personnel, 1,276 sweepers, 1,700 boats, and 400 planes, whereas the British Defence against Axis mining operations involved 53,000 men and 698 sweepers, plus many hundreds of fishing and auxiliary vessels.

 “Stirred and shaken”

War destruction at sea is usually counted in sunken merchant tonnage or destroyed enemy naval ships. During autumn 1939 already the total loss of merchant ships was of about 380 with a tonnage of 1 million, out of which the British, Allied and Neutral forces counted 320 vessels and about 900,000 tons.

 We are all aware of the attention paid today to the drama of only one ship that happens to sink in the sea. Well, imagine that during the autumn 1939 there were three sunken ships per day and that this terrible situation lasted for four months.

 In addition, the Royal Navy lost: one battle ship, three destroyers, one aircraft carrier, one armed merchant cruiser, approx. 10 trawlers, two U-boats, and an important number of smaller units. The German Navy lost 9 U-boats and from its bigger units the pocket battleship Graf Spee at La Plata, in December 1939.

However, the sinking of about 500 ships of huge dimensions with several thousands of dead sailors and service men aboard may tell a lot about the human and material loss, but very little about the climatic repercussions which have violently shook the seas. Since the beginning of the war, many hundred vessels ploughed the seas day and night in a series of naval activities. A battleship at a cruising speed of 30 knots turns “upside down” a water column of about 12 meters over an area of 72 square km in only 24 hours. In only one month, 300 such ship manoeuvres can “stir” the complete North Sea surface layer.

Anthropogenic actions severely affected the seawater climatic structure. Seen from this perspective, the coming up of a cold winter was inevitable, as explained in the next section.

 Seas reacted to naval churning

The theme

Although physical laws are the same for hot soup and for the “stirred” seas, things tend to become more complex when naval activities occur in the North and Baltic Seas. This happens because the location, seasons and acting forces are different and would not matter so much if science had organized a comprehensive and sufficient coverage of the temperature measurements throughout a seawater body, a long time ago. But such a system was not available before WWII and it is still not available today. Only a few coastal stations recorded sea surface temperatures for a longer period of time. This is by far too insignificant for the climate research. Only a complete picture of the interior of seas and oceans would help us detect and understand the climate course and changes.

But when the seas are the ones who determine the pace of weather and of climate, one can turn ‘the table around’ by using meteorological data and by citing deviations from usual atmospheric wintertime conditions, deviations which are due to the turning about of waters of the North and Baltic Seas.

This idea will be discussed under three aspects, namely:

• West wind drift and the seas steaming;

• The origins of the abundant rain;

• Sea ice conditions during winter 1939/40.

Europe’s northern waters

The North Sea

 The North Sea is one of the principal factors in European climatology. On one hand, the North Sea is part of the North Atlantic Ocean and has the aspect of a big bight. On the other hand, it draws a curve into the landmasses of the European continent. Climatic conditions are therefore transitory and its climate is neither maritime nor continental. Nevertheless, due to its geographical location, prevailing westerly winds travelling through the hemisphere within a zone of 2,000 kilometres width, usually ensure a temperate humid climate.

	North Sea diagonals (England – Continent)
Water depth	Southern section West/East	Middle section West/East	Northern section West/East
Surface	10/12.5 °C	8/15 °C	6/10 °C
7.5 m	11/13 °C	8/15 °C	5.5/10 °C
20 m	11/13 °C	7/13 °C	5.5/8.5 °C
30 m	11 °C	6.5/12 °C	5/7.5 °C
40 m	–	6/11 °C	4.5/6 °C
60 m	–	4,4 °C	4.5/3.5 °C
80 m	–	3,5	4.5/1.5
100 m	–	–	4/1.5

Water depths of the North Sea can be roughly divided into two sections. The southern section consists of a plateau, south of a line running from mid-England (Hull) up to Northern Denmark and which is less than 40m deep. The northern section is a triangle among Northern Denmark-Hull-Shetland Islands, with a water depth ranging between 60 and 120m (the deepest place measures 263 m), and the submarine valley along the Norwegian coast with depths ranging between 240 and 350 metres, and of 500-700m in Skagerrak. The inflow of warm water from the Atlantic Gulf current enters the sea in the north and influences the current system from the surface to the bottom in the northern part only. The 40m deep southern plateau is hardly affected by the northern water, but receives some Atlantic water via the Strait of Dover and some freshwater from the rivers. This way, the North Sea is rich in water masses of different types and origins, which vary and fluctuate every season and every year. As all coastlines are subject to significant tidal forces, considerable water masses actually vary on a daily basis.

The annual data of approximate temperature variation in three West-East diagonals across the North Sea is as it follows:

The southern section of the North Sea

Due to the shallowness and tidal forces of the water body, its temperature structure can be described as a homogeneous one (from surface to the bottom), with small variations as the average temperatures indicate: December (8.5°C), January (6.5-7°C), February (5.5°C), March (5°C), April (6.5°C), suggesting that water very close to the coasts has lower temperatures during the winter season.

Between May and August, temperatures increase from 8.5°C to 14.5°/17°C and decrease as it follows:

Depth	August	Sept.	October	November
Surface, West-East	14.5-17 °C	14-16 °C	12-13.5 °C	09°-10° (*)
20 m, West-East	14-16 °C	15-16.5 °C	13.5-14 °C	9.5-11 °C

(*) in the mid-North Sea, the figure is considerably higher than in West & East (with 11.5°).

Fairly homogeneous figures of the water body temperature, with 15°/16°C at peak time and the lowest temperature in March (5°C), indicate that the water body experiences an average change of about 1.5°C per month.

The northern section of the North Sea

In March, the lowest annual average temperatures at the surface of the water ranged between 7°C in the northwest (Atlantic water) and 4.5°C in the southeast (Dutch coast). At the end of August, the highest average temperatures at the surface of the water ranged correspondingly (NW and SE) between 13°C and 17.5°C in the Helgoland Bight.

From May until August, a horizontal thermo-cline builds up, but declines during the autumn months. Temperature level increases at lower water levels (e.g. 20m, 40m) in autumn and decreases at the bottom (60m). It is therefore possible for the whole water body to be warmer in September than in August. Even if, after calculating the ‘monthly averages’, we get only an approximate figure, this gives us an indication about the monthly decrease in temperature (or energy release) which takes place in small quantities: from 11°C in August to 4.5°C in March, i.e. on an average it could be as little as only one degree per month.

[i] German daily weather charts of ‘Seewarte’.

6 Source:www.usafa.af.mil/dfh/harmon_series/docs/Harmon36.doc.

 

 Continues: Chapter B (p. 28-39)

 

 

 The following text is the prewvious online version

Arctic winter 1939/40

General winter weather scenario Get the PDF!

If war at sea changes the climate, such an event would have tremendous political implications. If there are significant political implications in 2006,there must have been in 1939 too, but unfortunately no one knew what was at stake at that time.

Winter conditions in Northern European Countries Get the PDF!

On the 1st of September 1939, Germany launched land, air and sea attacks on Poland. Soon, the Nazis deployed 5,000 planes upon Poland. On the 25th of September 1939, 240 German planes bombed Warsaw, dropping 560 tons of bombs (including the first bomb of 1,000 kg). 30 transport aircrafts dropped 70 tons of firebombs.

Seas churned by navies. Laws of physics governing Hot Soup in a Cup Get the PDF!

This investigation is not concerned with naval history but with global warming, respectively climate changes. Describing military events in Europe since September 1939 would require any historical writer to make the distinction between activities on land, in the air and at sea. Military aspects interest us only as far as they affect the climate.

“A spoon in a cup” Get the PDF!

Dimension does matter if one considers the effect of stirring the soup in a bowl with a spoon. In oceanic terms, the enclosed seas of Northern Europe represent only 0.2% of global sea surface and a mere drop with respect to the total volume of the seas around the world (0.0026%). Nevertheless, they play a crucial role as their size represents roughly one-third of North-western Europe. As for the effect of the ‘turning about’ of the sea areas, their depths are of considerable importance.

Naval Fleets

By December 1939, the number of main naval ships belonging to Germany, Great Britain, France, Italy, the Soviet Union and Italy amounted to more than 1,000 vessels (including submarines, torpedo boats, etc.), with a total tonnage of 2.8 million plus at least another thousand smaller vessels and boats serving as mines sweepers, etc.

The Merchant Fleet and the Convoy System Get the PDF!

As far as Britain was concerned, shipping activity was of utmost importance, so no effort was spared in order to maintain this. Atlantic supremacy should ensure sufficient supply to Great Britain at any time. Allies introduced the convoy system without delay, this strategic display having been very successful during WWI. The convoy system was supported by the First Lord of the Admiralty Winston Churchill who once said that it was \”the dominating factor all throughout the war… Battles might be won or lost, enterprises might succeed or miscarry, territories might be gained or quitted, but dominating all our power to carry on the war, or even to keep ourselves alive lay our mastery of the ocean routes and the free approach and entry to our ports\”.

Submarine—U-boats Get the PDF!

British submarines had the difficult task of intercepting well protected German shipping around Northern Europe by direct torpedo attacks or by mine laying missions. Although Britain never managed to operate in the Baltic Sea during WWII, Royal Navy submarines took its heavy toll of German troop transporters, supply ships and escort vessels, quickly forcing the Germans to adopt the system of defensive convoys when operating in the North Sea or, since 1940, in the Norwegian waters. During the Second World War, British submarines were credited with the sinking of 475 merchant ships, 105 warships and 36 submarines, and with the damaging of many others.

Depth Charges Get the PDF!

This section is about ASW, namely anti-submarine-warfare. A depth charge is a ‘drum’ containing explosives with a fuse which is detonated at a preset depth and which is based on hydrostatic pressure. Developed in 1916, during WWI, a depth charge could detonate up to 100m depth and carried 150 kg of explosives. There was little development for this weapon between the wars except for a 300kg variant. At the start of WWII, depth charges were essentially the same weapon as it existed at the end of WWI. This situation changed quickly. In September 1939, The New York Times wrote about the procedures of U-boat hunting: “Once a submarine is located, British naval plans, so far as they were known before the war, call for attack by familiar methods of an enclosing diamond pattern of depth bombs, supplemented, of course, by shell fire and ramming if the submarine could be forced to the surface. In the diamond-pattern attack, the destroyer goes at full speed to the spot where the submarine, slow and clumsy under water, is thought to be. One depth bomb is charged just before the spot is reached. A few seconds’ later two more are lobbed out by a Y-gun so that they land out on either side of the destroyer’s wake. In the front part of the diamond pattern, another depth bomb is dropped over the stern, some distance ahead of where the Y-gun fired. This way a large area of the sea is covered by this diamond pattern. The effect is further increased by the fact that the bombs are timed to go off at different levels, so that the area is covered not only horizontally but vertically as well. The bursting area of a modern depth bomb is considerable”.

Aerial bombing at sea Get the PDF!

Neither the German navy nor the British one had a fully operational aerial arm at the beginning of WWII. The German Navy never got one. British Royal Air Force Coastal Command became operational in 1940. However, airplanes charged with bombing missions were operating frequently (British airplanes in the Helgoland Bight and German airplanes on England’s East coast) or were attacking the enemy in the open sea. On the 3rd of September 1939, Britain was in possession of a fully operational unit of 2,600 aircrafts; the Germans had nothing less. A few out of many hundred events are listed below in order to offer you an outline of what happened during the first few months of the WWII.

Sea mines

Between 100,000 and 200,000 sea mines have been laid during the few autumn months of 1939. Most of the mines were placed in the North Sea and a substantial number in the Baltic Sea.

East Coast Barrier Get the PDF!

The British successfully mined their East coast from Dover to Orkneys during the first few months of the war. In September 1939 alone, the British minelayers Adventure and Plover laid 3,000 mines across the Strait of Dover. In the second half of September, the barrage was completed with 3,636 U-boat mines, which soon paid results, Germany losing three U-boats in October. The British set up the East Coast Barrier, a mine barrage between twenty and fifty miles wide, from Scotland to the Thames, leaving a narrow space for navigation between the barrage and the coast. In early January 1940 The New York Times reported: “British naval vessels are sowing some of the last mines needed to complete Great Britain’s 30,000,000-pounds protective shield for east-coast shipping, which is the most extensive mine field ever laid.” If one assumes that the weight of those mines varied between 300 and 1,200 pounds, the number of mines laid in autumn along the east coast alone would be between 25,000 and 100,000 mines.

Helgoland Bight (Deutsche Bucht) Get the PDF!

At the beginning of the war, the German Navy laid a large mine field starting from the Nethelands’ coastal waters (near Terschelling island) and going northwards across the Helgoland Bight up to the entrance of the Skagerrak, at a distance between 50 and 100 km off the coast of Schleswig-Holstein and Denmark. This barrage was known under the name of “Westwall”. For about three weeks, a flotilla of at least 25 naval vessels was engaged in laying mines along this “Westwall”. The number of mines laid during the period in question could be somewhere between 20,000 and 200,000. But as the distance from Terschelling to 56° 30’ North is of about 350 kilometres (170 sea miles) and the 25 naval vessels charged with this task were able to lay thousands of mines per day, it seems reasonable to assume that, by the end of the year, the Reichsmarine could have placed somewhere between 50,000 and 100,000 mines.

Mining the Baltic Sea—1939

War had just started when the 1,555-ton, Greek ship Kosti hit a German mine, two miles south of Falsterbo/Sweden, on the 4th of September, and sank after a terrible explosion in the minefield in the south of the Great Belt and the west of the Danish island of Zealand. Danish Government made public its plans of planting mines in its own waters. From the very first days of the war, the Germans had laid about 1,000 mines at the entrance in the Danish waters and they continued to lay mines during autumn as well. In the early November, gales had loosened several hundred mines from the German mine field, drifting them off the Copenhagen shore, where some of them exploded, breaking windows and frightening citizens with the terrific noise of their detonations.

Minesweeping Get the PDF!

Minesweeping activities were another particularly effective means of churning and turning huge sea areas day-by-day, since the war started. A standard mine was the moored contact mine, a buoyant material filled with up to 1,000 kg of explosive. To avoid detonation, special ships used distant means to cut the mooring chain or wire attached to the mines to keep them afloat. Sometimes, the mines exploded before reaching the surface and if they surfaced they were blown up with rifle shots. In November 1939, magnetic mines entered the scene. They could only be destroyed through forced explosion. From the climatic point of view, this was the worst case scenario. The mine was exploding in its location, at a depth of 20 or 50 metres, producing the biggest possible “stirring” effect in the water column reaching above. The countermeasure was to deactivate the ship’s ‘magnetism’ so that it could pass near the mine without activating it.

“Stirred and shaken” Get the PDF!

War destruction at sea is usually counted in sunken merchant tonnage or destroyed enemy naval ships. During autumn 1939 already the total loss of merchant ships was of about 380 with a tonnage of 1 million, out of which the British, Allied and Neutral forces counted 320 vessels and about 900,000 tons. We are all aware of the attention paid today to the drama of only one ship that happens to sink in the sea. Well, imagine that during the autumn 1939 there were three sunken ships per day and that this terrible situation lasted for four months.

Seas reacted to naval churning. The theme Get the PDF!

Although physical laws are the same for hot soup and for the “stirred” seas, things tend to become more complex when naval activities occur in the North and Baltic Seas. This happens because the location, seasons and acting forces are different and would not matter so much if science had organized a comprehensive and sufficient coverage of the temperature measurements throughout a seawater body, a long time ago. But such a system was not available before WWII and it is still not available today. Only a few coastal stations recorded sea surface temperatures for a longer period of time. This is by far too insignificant for the climate research. Only a complete picture of the interior of seas and oceans would help us detect and understand the climate course and changes. But when the seas are the ones who determine the pace of weather and of climate, one can turn ‘the table around’ by using meteorological data and by citing deviations from usual atmospheric wintertime conditions, deviations which are due to the turning about of waters of the North and Baltic Seas.

Europe’s northern waters. The North Sea

The North Sea is one of the principal factors in European climatology. On one hand, the North Sea is part of the North Atlantic Ocean and has the aspect of a big bight. On the other hand, it draws a curve into the landmasses of the European continent. Climatic conditions are therefore transitory and its climate is neither maritime nor continental. Nevertheless, due to its geographical location, prevailing westerly winds travelling through the hemisphere within a zone of 2,000 kilometres width, usually ensure a temperate humid climate.

The southern section of the North Sea Get the PDF!

Due to the shallowness and tidal forces of the water body, its temperature structure can be described as a homogeneous one (from surface to the bottom), with small variations as the average temperatures indicate: December (8.5°C), January (6.5-7°C), February (5.5°C), March (5°C), April (6.5°C), suggesting that water very close to the coasts has lower temperatures during the winter season.

The northern section of the North Sea Get the PDF!

In March, the lowest annual average temperatures at the surface of the water ranged between 7°C in the northwest (Atlantic water) and 4.5°C in the southeast (Dutch coast). At the end of August, the highest average temperatures at the surface of the water ranged correspondingly (NW and SE) between 13°C and 17.5°C in the Helgoland Bight. From May until August, a horizontal thermo-cline builds up, but declines during the autumn months. Temperature level increases at lower water levels (e.g. 20m, 40m) in autumn and decreases at the bottom (60m). It is therefore possible for the whole water body to be warmer in September than in August. Even if, after calculating the ‘monthly averages’, we get only an approximate figure, this gives us an indication about the monthly decrease in temperature (or energy release) which takes place in small quantities: from 11°C in August to 4.5°C in March, i.e. on an average it could be as little as only one degree per month.

The Baltic Sea Get the PDF!

In terms of size, the Baltic Sea is a mere ‘drop’ of water in the world’s oceans, but thanks to its strategic location and specific features it represents a ‘significant’ force and influences the weather in the countries surrounding it. It is an excellent location for the climatology study. The total area of the Baltic Sea is of 400,000 square kilometres, with an average depth of 55m (including the Gulf of Bothnia, 55-294m and the Gulf of Finland, 30m). Except for the eastern part (Gdynia Bight with a maximum of 114m), the southern Baltic Sea is less than 50m deep. An important climatic feature of this sea is a 2,500m high mountain ridge going from the north to the south of Norway and drawing a sharp line between maritime and continental areas. Continental and polar air has much easier access behind this barrier than it has in areas where the Atlantic air travels east at a lower level. This mainly guarantees warm summers to Baltic countries by significantly delaying the arrival of continental winter conditions. There is hardly any other sea in the northern hemisphere which can convincingly illustrate the importance of the heat storage and release process throughout all seasons the way the Baltic Sea does.

Westerly winds Get the PDF!

The western European weather is famous for the predominant flow of wind blowing from the North Atlantic above the Euro-Asian landmasses (from west to east). The wind brings warm air from the depression but soaked up with humidity from the ocean. In contrast, anticyclones influence the weather conditions through high air pressure combined with dry and cold air masses.

The reaction of the North and Baltic Seas Get the PDF!

North and Baltic Seas play their role according to the physical laws. By the end of August, they had reached the highest seasonal heat capacity. At this time, the upper water column (down to 30 meters depth) is about 10°C warmer than six months later, in March. If no unnatural phenomena come up to stir the seas, then only usual winter winds and storms make waves and only the internal currents exchange the cold water with warm water at the surface of the sea. In this case, seasonal cooling (from September to December and to March) occurs gradually, but close to long term statistical average. That is what climatology tells ever since: “climate is average weather over a long period of time”.

Why did it rain cats and dogs? Get the PDF!

In the previous section, we offered an overview of the winds changing direction and blocking cyclone influence in Western Europe. We saw how excessive evaporation determined air to flow in from north-east. But what happened with the increased humidity of the air? What chain of physical phenomena was set in motion?

a. The general picture

First and most important picture: when there is less humidity in the air, it is easier for the cold air to take control. During the winter season, when the Northern Atmosphere is drier, general circulation decrease makes it easier for the polar air to travel to southern latitudes and to determine lower temperatures in many other regions. Some may even wonder about the appearance of such arctic conditions. January 1940 reflected this exact situation. North America, China and Europe froze under extreme low temperatures and there was plenty of snow everywhere. We will first deal with the excessive rain in Western Europe and then, in a subsequent section of this chapter, with the situation of North America in autumn 1939 and January 1940. However, the record winter of 1939/40 in North Europe was ‘homemade’ due to naval warfare in its seas and to the forming of ‘dry air’, which may have been responsible for the extreme cold month of January 1940 throughout the Northern Hemisphere.

b. Where did all the water come from? Get the PDF!

One can discuss the matter under two aspects: 1. where did so much water vapor come from? 2. how was it brought down?

USA dried out Get the PDF!

The ‘rainmaking’ in Europe had a very interesting consequence on the other side of the globe. In the late autumn of 1939, the U.S.A. ‘fell dry’ after receiving only a small percentage of normal precipitation: in October 78%, in November 44% and in December 71%. On the 7th of January 1940, The New York Times reported that November was an unusual month because of its dry air. According to US Weather Bureau “the fall season was extremely dry over large areas. From the Rocky Mountains eastward it was the driest fall on record considering the area as a whole.”

The icing of the sea—Winter 1939/40 Get the PDF!

Icing along the Danish, German and Finnish coasts started early and sea ice conditions lasted longer than in dozens of previous years. This proves that the sea water along all coasts was too cold for that time of the year.

Chapter summary

While the previous chapter described the severity of war winter 1939/40 on one hand, and the naval activities during four pre-war months on the other, this chapter attempted to link anthropogenic causes with corresponding reactions in regional environment. As navies churned huge sea areas about, the evaporation of the seas increased and eventually changed the prevailing winds, declined the movement of the Atlantic depression on common routes and caused record deviations of the sea water temperatures. At least in one case, the build-up of sea ice conditions in the North and Baltic Seas demonstrates several aspects of the naval war and of its implication in environmental issues.