Lake effect snow
Especially in the Great Lakes in North America occurs on a meteorological effect that is referred to there as Lake effect snow or snowsquall. A German term for this phenomenon does not exist, but you can translate the English names with lake-effect snow or Seewirkungs snow or Schneeböe.
This effect occurs when the winter cold winds flow over large lake areas with warm water. It is absorbed through the lake steam, but the freezes quickly and goes down on Lee - shore of the lake as snow. The effect is enhanced by orographic induced upward movements of air flow against the wind direction, which can lead to narrow but very intense bands of precipitation with deposition rates of several tens of centimeters of snow per hour ( see right).
Cold air winds blow in winter the northern West wind zone typically from west-southwest to northwest, so occur the most snowfall in the northeast to southeast shores of the lakes. The result is a significant difference in the amounts of precipitation for the opposite bank and its direct hinterland. If the air temperature is not low enough to keep frozen water, the precipitate shows as lake-effect rain.
The weather records of the Tug Hill Plateau in the south-east of Lake Ontario consistently highlight the highest snowfall values for the entire United States. Another example is the area in the southeast of Lake Erie, with an approximate spread of Cleveland to South Buffalo, with Lake Erie, due to its shallow depth, but also easily freezes and the effect no longer shows. Also at the south and southeast coast of the Great Salt Lake in Utah lake effect snow can occur, but this one is much less pronounced than in comparison to the Great Lakes. These areas of influence of lake effect snow man known in English as snowbelts (Eng. snow belt). The snowbelt with the largest volume of lake effect snow is in the Upper Peninsula of Michigan, near the cities of Houghton, Marquette and Munising. These areas often have snow reports from an average of 5 or even 7.5 meters a year, do not reach their low colonization but the notoriety of the other areas around the Great Lakes. Since the adjacent Lake Superior because of its size and depth rarely freezes over, the effect shows here often continuously throughout the entire winter months.
In early winter can lead to strong thunderstorms, known as thundersnow extremely cold air over summer conditionally still quite warm water areas. But even if no precipitation occurs, so always causes cold air above warmer water, a heavy cloud over the southeast coasts of the Great Lakes, which is why we used here the term The Great Gray Funk as a synonym for the winter. As a result of the lack of light, it therefore frequently in these areas to winter depression.
Similar snowfall can occur near large inland bays, where they are then referred to as bay effect snow. If the cause is a low pressure area on the ocean, the humid and unstable air masses often draws on coastal areas, contrary to the prevailing wind direction, one also speaks of a ocean effect snow.
Lake effect in Germany
In Schleswig- Holstein the effect was most recently on 11 March 2013, as especially the city of Lübeck was affected. In some parts of the city it was snowing continuously for more than 24 hours, thereby locally about 50 cm of fresh snow came together. Previously, he also joined already on 30 November 2010 on the middle part of the circle East Holstein, as polar easterlies over the warm Bay of Lübeck shortly led to snow depths of up to 76 cm and significantly higher snow drifts, so that the traffic collapsed on the streets.