Chapter B – Part II
Page 28-39 – NOTE: All book images replaced – Published by iuniverse/USA
Autor: Dr. Arnd Bernaerts (date of publication 2006)
The Baltic Sea
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.
Actually, very cold conditions cannot last long on sea and nearby coastal areas as long as the sea is open and not iced. Icing is regarded as a critical point in the regional climatology. Every sea area covered with ice loses ten times less energy to the atmosphere than an open sea area. The importance of the heat flux can be clearly illustrated by the records of temperature data which show that winter average temperatures at the seaside are considerably higher than inland temperatures which sometimes decrease in great leaps, i.e. by 1°C per 50 km or even more (depending on their distance from the coast).
Between mid-September and the end of February, when the air is colder than the seawater, water temperature decreases between 13°C and 15°C, which is significantly more than that of the North Sea (9.5-11.5°C). This actually means that the surface temperatures, with an average ranging from 0°C (north) to 3°C (south) in January, quickly come close to zero. Deeper waters (80 metres and below) have just 4-5°C, while the water column above varies according to the seasons. These changes of temperature during various seasons are effective only from the surface to about 80m depths. While surface water reaches its peak temperature by the end of August, lower levels may reach their peak later on (e.g. 10°C at 40m, in late October). Therefore, all activities that took place at sea during the autumn 1939 could have had three principal effects:
The churning of the upper sea water layer and the increase of evaporation cause a soup cup effect.
The turning about of the seawater masses will force warm water masses to greater depths. Later on, these warm masses will ‘resurface’ thus bringing about milder air (as usual) or delaying the icing processes by days or weeks.
Any increased evaporation in autumn will cause the inevitable cool down of the sea water body. The less warm water is available, the colder the air above.
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 war machinery changed the weather blueprint so quickly and decisively that after only a few weeks of war the westerly winds were already sealed off from passing through Central Europe.
The reaction of the North and Baltic Seas
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”.
However, statistics become useless if a spoon stirs forcefully a cup of hot soup or if naval forces interfere and turn seas up side down. Warm water starts to steam. The more water is turned and twisted, the more steam goes up. This is exactly what happened in autumn 1939. Seawater around Britain (particularly in the southern North Sea, Helgoland Bight, and Baltic Sea) was forced to evaporation at a rate above any other climate data average. Air above the seas became ‘thin’ and needed replacement with ‘heavy’ air, which was abundantly available in Northern Russia and in the Arctic region. Consequently, cold air travelled from North to Eastern and Western Europe. Prevailing north-east winds should be regarded as strong evidence that naval warfare acted in North and Baltic Seas the same way a spoon rapidly mixes the hot soup in a cup.
This phenomenon became evident the moment the German weather service reported that the wind direction has changed dramatically (the 2nd of November 1939). Based on immediate observations in Northern Germany, meteorologists noticed that the wind blowing from North-East had almost doubled its presence, while the most prevailing South-Western wind (usually 24%) accounted now for only 9%. This is a very strong and clear indication that huge air masses moved towards the North Sea and to the southern part of the Baltic Sea, phenomenon caused by unusually high evaporation in this area of the sea. While the North Sea water was ‘stirred and turned’, ‘steam’ rose upwards into the sky and determined air from the north-eastern area to flow in, thus preventing low-pressure cyclones to travel along the west-wind-drift channel via the North Sea to Central Europe and further on to Asia.
During the first days of December, we witnessed the last weak attempts of the cyclones to reclaim their common path of travelling east. By the 7th of December 1939, a high pressure coming from Belgium to Norway served as the last stitch for the installation of severe winter conditions. Humid Atlantic air seemed to have lost the game. The ‘Neue Zürcher Zeitung’ (the 14th of January 1940) analysed the situation as it follows (extract):
“The severe cold which invaded t
he whole Europe this week was by no means an accidental phenomenon that settled in by surprise. It rather represents the peak of a gradual process which had its beginnings during the first week of December. Towards the end of the phenomenon, high pressure began to stabilize in Northern 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 Seas, they were immediately replaced by cold air coming in from the Greenland area.”
This is an impressive analysis. What the weather expert did not realise is the fact that the ‘blocking’ of the western winds had occurred since September 1939 and that war at sea was to be blamed ever since.
At this stage, it might be worth mentioning that a research conducted by Kew Observatory (London) in the early 1940s mentioned that prevailing wind directions in South-Western England during 155 winters (from 1788 until 1942) had only 21 easterly resultants, whereby the few winters 1814, 1841, and 1940 had resultants from NE to E-NE. Another few winters after 1841 (1845, 1870, 1879, 1891, 1895, 1904, 1929) were characterized by prevailing winds coming from S-SE to E-SE, but during all the other 130 winters the westerly wind prevailed. The exceptional situation of the first war winter (1940) is thus clearly underlined.
Why did it rain cats and dogs?
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?
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.
The next important picture is about the situation in which precipitations actually ‘dilute’ the atmospheric humidity. If it rains abundantly in one place, precipitations statistically diminish in other places until humidity restores average equilibrium again. This process may take more than a few weeks. If war can cause abundant precipitations during the winter season, nature needs much more time to ‘fill’ the gap during the summer season. So far this information represents only physical laws and not facts.
Hardly had WWII started when it began to rain excessively in Western Europe, from Berlin and Basel to Paris, Amsterdam and London, for three months: 200% above average in September, 300% in October, and more than 200% in November. Greenwich saw a higher rainfall only in 1888, and before that in 1840. In some places at the southern end of Maginot/Westwall Line there were recorded 30 days of rain during October 1939. A number of other locations had up to 24 days of rain.
The appearance of all the excessive rain in West Europe raises an essential question: where did all that water vapor come from?
Where did all the water come from?
One can discuss the matter under two aspects:
where did so much water vapor come from?
how was it brought down?
Since the 1st of September 1939, a huge defense area going from Basel to Dunkerque (Maginot Line) and from Basel to Emden (Westwall) was activated and guarded by one million soldiers on each side. From that moment on, encounters of different proportions, shelling, air fights, and aerial bombings occurred frequently. On the 7th of September 1939, 700 French tanks moved several miles into German territory, while 300 airplanes attacked German positions in an industrial region and munitions area, some 125 miles farther north.
Meanwhile, explosions of sea mines and of depth charges, shelling among enemy ships or ships versus coastal battery, and thousands of ship movements churned and turned around the waters of the North and Baltic Seas. Evaporation rate increased significantly. Water vapour attracted cold air flowing in from the north-east and pushing the excessive water vapour in the south-west, towards Westwall and Maginot Line, including South England. There started a record rain period for which we state three reasons:
Naval activities ‘produced’ a high and constant humidity all over the western war front, including the SE of England, North of France, North of Switzerland, Bavaria, and, further north, the Netherlands, the West, Middle and South of Germany (including Berlin and Silesia).
Water vapour condenses using the molecules as condensation nucleus. Condensation occurs on a wide variety of aerosol particles g. particles of dust, salt, desert sand or smoke. Ambushes and burning down of villages and cities in Poland (in September) and frequent military encounters on the front lines produced abundant condensation nuclei. Clouds formed and eventually ‘burst’ into rain.
North-easterly air was cold. When high humid air laid over Western Europe and resisted being pushed farther south, arriving air would cool down the high humid air and it would inevitably rain.
A Reuters’ report from the 5th of May 2006 can help us demonstrate that the Second World War activities played a major part in the phenomenon of rainmaking: Chinese technicians have artificially generated heavy rainfall. 163 pieces of cigarette-like sticks containing silver iodide were burned and launched by seven rocket shells in six districts and counties for a cloud seeding operation, which resulted in the heaviest rainfall in Beijing in this spring.
The scenario seemed perfect: plenty of water vapour in the atmosphere, abundant condensation nuclei and a constant cold air incoming from the north-east. All these physical conditions lead to abundant rains in Western Europe.
USA dried out
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.”
After three months of poor rains, the soil and ground were too dry and thus unable to supply the atmosphere with humidity through evaporation. The door was open to polar air. On the 13th of December, Mountain View, Franklin County, New York had already reported a temperature of minus 20°F (= -29°C). Before the end of the year, winter brought “a biting northerly wind, driving gray, snow-laden clouds.” It was New York’s coldest winter day before the New Year’s Eve: down to 12°F.
Arctic air from the North was attracted by the dry American continent around Christmas and the U.S.A. remained under its influence until the end of January 1940.
The icing of the sea – Winter 1939/40
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.
Denmark-Sweden: First signs of ice were reported around mid-December and they increased soon in the inner, closed waters. A maximum of 115 ice days was reported. While 34 stations reported more than 100 days, 99 stations reported 75-100 days. Last ice was reported in the Sounds on the 19th of April 1940. Because of the early start of the winter, it remained known as the severest ice conditions on sea for many decades.
North Sea – Helgoland Bight: Icing and ice floats emerged on river Elbe on the 16th of December 1939. In Hamburg, about 100 kilometres of river upstream from Helgoland Bight, at a mere 80 km distance from the Baltic Sea, there had been constant temperatures of sub-zero degrees Celsius since the 8th of December. Icing intensified massively since the 26th of December and extreme ice conditions maintained for 90 days, until mid-March 1940.
First ice arrived in Helgoland Bight, on the 17th of December 1939, and lasted until early March.
Southern Baltic Sea: Conditions for building up the ice differed in three ways from the average of previous years.
Ice formation started first in the southern Baltic Sea in mid-December 1939, and
Full icing in the Gulf of Finland started only with the cold wave on the 14th-24th of January 1940.
These events should not come as a surprise if one takes into consideration the German naval activities of the Kriegsmarine in the southern Baltic Sea: the ambush of Polish coastal defence, the laying of extensive sea minefields, the patrolling and the training of the crews.
In the South, at Greifswald Bodden (an open bight in the SE of the Rügen island), icing started on the 18th of December 1939. Solid ice remained intact in place until the 4th of April 1940. Last ice disappeared on the 11th of April 1940.
Northern Baltic Sea: The waters around Finland had never seen so much ice as during the war winter 1939/40 since 1883. And since the 30th of November, the region was especially affected by the most devastating war winter ever seen under the Arctic Circle where the sun never shines for many weeks. On land, the Russian Red Army attacked with more than 300,000 men on a front of one thousand kilometres length. At sea, the Russian Baltic Fleet attacked Finnish shore batteries on islands and coastal points with big shells. Submarines operated in the Gulf of Finland and in the Gulf of Bothnia, and laid many thousands of sea mines. Finish Navy was small but still operational. Because of the intense naval activities, the picture of the icing seems to be unclear at the first sight, which is not the case. It actually confirms that naval activities influenced substantially the sea-icing process.
Not to forget that the formation of sea ice started first in the southern Baltic Sea, along the coastline of Germany. In Hanko/Finland (at the west entrance in the Gulf of Finland), icing started on the 27th of December 1939; solid ice formed on the 4th of January 1940; the end of ice came on the 7th of May 1940, at almost the same time as in Helsinki. However, on the 15th of January 1940, the Gulf of Finland was still open as far as Pellinki. The Gulf of Bothnia was also open in most of its parts. Ice then formed rapidly. Although the Gulf of Bothnia is far in the North and its depths measure more than 200 metres – in the Baltic Sea area – it is the deepest water, holding considerable heat for considerable time even during cold winters. An ‘ice-bridge’ between Turku and the island of Åland (a depth of maximum 30 m) formed on the 6th-7th of January 1940, about 2½ weeks earlier than usual.