Cold spell
A cold spell is a relatively short period of time when the air temperature drops sharply to below average . Both at the beginning and at the end of winter one speaks of the onset of winter.
Meteorological basics
Cold waves start when deep -reaching cold air from the area above the Arctic can penetrate far south in connection with a strong development of low pressure on the back of a high trough (see also polar vortex ). Above a blanket of snow, the air temperature can reach extremely low values due to radiation .
Conditions in Europe
In Central Europe , cold waves occur in winter, particularly through the advection of very cold mainland air from the north-east. The classic action center is a dominant Russian high above Siberia, which leads large-scale arctic cold air to Central Europe. Sometimes this Siberian high pressure area forms a high pressure wedge as far as Scandinavia, so that at the same time low air pressure over the Mediterranean Sea with an easterly current, cold air can advance as far as southwestern Europe.
For Central Europe, the cold waves are mostly well-documented singularities (regularly occurring exceptions), in the cold half of the year, early in mid-October to late in the ice saints as winter or high winter phases, in the warm season as intermediate phases of summer warmth. They arrive with significant frequency around certain appointments, but can fluctuate greatly around them or fail completely.
North America
In contrast to the arctic polar air in Europe with the Alps as a weather divide, the icy, freezing cold from the Arctic can penetrate further south due to the geological conditions in North America and reach Canada as well as the USA. Due to the arrangement of the mountains on the continent in a north-south direction and the lack of warming over a sea, minus temperatures 20 degrees Celsius below zero with pronounced temperature jumps can affect millions of people. At the beginning of 2019, a cold spell reached southern Canada and the midwest and northeast of the United States at minus 31 degrees Celsius in Chicago. The jet stream also plays a different role than in Europe.
See also
- Millennium from 1708/1709
- List of weather events in Europe (sortable also for cold anomalies)
- Natural events and accidents in East Prussia
- Siberia high
Web links
- 10 costliest winter storms with storm surges ordered by overall losses (pdf), Munich Re
- Austria's cold waves of the past 50 years , Die Presse online (Source: ZAMG )
- Federal Office for Meteorology and Climatology : Records and Extremes
literature
- Meyers Lexikonredaktion (Ed.): Meyers Kleines Lexikon. Meteorology , with the support of the German Weather Service . Meyers Lexikonverlag 1992, Mannheim / Vienna / Zurich, pp. 199, 202
Individual evidence
- ^ Meyers Lexikonredaktion (Ed.): Meyers Kleines Lexikon. Meteorology . Meyers Lexikonverlag, Mannheim / Vienna / Zurich, p. 351.
- ↑ Karsten Schwanke : Now extreme cold - in three days of spring , Die Zeit , February 1, 2019.