17 
In mild winters, the ice in Szczecin Lagoon usually begins to form in the third decade of 
December. It is up to 10 cm thick, covering the Lagoon area for approximately one month. In 
January, thin ice may appear for three days at the coast of the Pomeranian Bay. The Lagoon 
area becomes free of ice by mid-February. 
2.2. Meteorological and ice conditions in moderate winters in the period 
1961-1990 
2.2.1. The meteorological conditions are described for the moderate ice winter of 1976/77. 
November 
Negative minimum temperatures in the area of Szczecin Lagoon were recorded from 20 to 25 
November, with values ranging between -0.5 to -4.4° C. Negative mean daily temperatures 
were observed on 24 and 25 November. In response, the water temperature decreased from 
6°C on 20 November to 2.8°C on 25 November. Then the water temperature rose slightly 
again. 
December 
In the first 10 days, westerly air flow over Northern Europe changed gradually to a largely 
stationary depression. Numerous secondary centres of this depression - some of them crossing 
the Baltic Sea Basin - were, however, blocked on their farther way east, by an anticyclone, 
which was formed over Eastern Europe. The westerly air flow was not very intensive and a 
gradual cooling continued over the continent. Mean daily air temperatures in the area 
remained positive. Between 11 and 17 December, the anticyclone from eastern Europe 
oscillated between Scandinavia, the British Isles, and as far as south-west Europe. As a result, 
the air stream over the Southern Baltic Sea veered north-east, now with a rich admixture of 
cool continental polar air. This airflow led to mean daily air temperatures between -1.2°C on 
14 December and -2.9°C on 18 December (Trzebiez) in the area of Szczecin Lagoon. The 
response of the water temperature was a decrease from 1.9°C on 14 December to 0.6°C on 18 
December. During these days, also a snow cover formed in this region. From 21 to 24 
December, warmer south-easterly air reached the southern coasts of the Baltic Sea, and water 
temperatures did not decrease further. Between 25 and 28 December, another intrusion of 
Arctic air, accompanied on 26 December by strong and gusty (exceeding 18 m/s) winds, 
caused mean daily air temperatures to fall from about -2° to about -4°C around the Lagoon. 
The last portion of Arctic air in this cold spell reached the southern coasts of the Baltic Sea on 
28 December, and in favourable radiative conditions of the following days the air cooled 
considerably: mean daily temperatures dropped below -9°, and the minimum temperature in 
Trzebiez was as low as -15.6°C on 31 December. Water temperature in Trzebiez decreased 
from 0.4°C on 24 December to 0.1° on 29-31 December. 
January 
In the first six days of the month, southerly air flow over Central Europe was steered by an 
anticyclone, which oscillated over Eastern Europe. Air temperatures around Szczecin Lagoon 
were close to 0°C. On 6 January, two high pressure centres merged into a single system which 
extended zonally from the Atlantic off the British Isles to the Caspian Sea. The air flow along 
the coasts of the Baltic Sea veered west, but mean daily air temperatures remained close to 
0°C, falling only on 9 January to about -3°C due to night radiation. The minimum temperature 
was -4.5°C. From January 10, a stationary depression settled over Central Europe, which was 
transformed into a pattern of very mild gradient at times. Stagnant conditions favoured 
gradual cooling. In the transformed maritime polar air spreading over Szczecin Lagoon, mean