Late winter

In meteorology, late winter is the late phase of winter , generally the period from mid- February to mid- March . According to other concepts, it specifically describes the first half of February.

These four weeks , meteorologically / climatologically mostly from February 15 to the beginning of spring as part of the winter meteorological season , overlap with the concept of the meteorological beginning of spring on March 1, which is set to the beginning of the month for statistical reasons. The term is therefore used less for statistical than for synoptic meteorology and related disciplines such as snow science and phenology . The late winter follows the high winter and leads into the early spring . Typical for the late winter of temperate latitudes is the end of the high winter period of frost ( ice days ) and the breaking up of the snow cover , which can extend into April or even May at higher altitudes and latitudes . Frost days (lowest temperature below zero) in late winter are still the norm, Innsbruck and Bern, for example, have an average of around 100 frost days / year, i.e. a full three months, and Germany a February mean temperature (1761–2009) of 0.0 ° C. Simultaneously with the higher air temperatures , more unstable general weather conditions set in , so that the late winter is less clearly characterized in the course of the year than the high winter, and also fluctuates more strongly depending on the year.

In the 1940s, Hermann Flohn used the term late winter (abbreviated Ws) as a singularity on the 3rd – 12th. February specified. This definition describes a high pressure situation typical for Central Europe , which according to more general concepts is still counted as midwinter. Other authors then also defined a first and second late winter , for example in the interval 5–19. February resp. February 20–11. March. However, subdivisions of the meteorological seasons that are too fine-grained have not caught on; they are mostly too local or, with occurrence frequencies around 50%, are not significant enough. In addition, they change with long-term climate fluctuations, such as global warming in the 21st century: For Germany, for example, the (first) late winter singularity averaged over the normal climatic period 1961-90 is easily detectable (for the date February 15-17), for 1991 –2017, however, only a constant temperature in the first half of February, which interrupts the regular rise in temperature; a second late winter can only be seen in the 100-year average for the values ​​from 1881 to today.

In peasant rules - early systematization of weather observations - Mariä Candlemas , February 2, is generally considered to be a lottery day between high winter and late winter, because from then on forest work ends and field work begins again .

literature

• Peter Bissolli, Christian-Dietrich Schoenwiese: Calendar -related weather phenomena in a new light. In: Naturwissenschaftliche Rundschau. 44 (1991) 5, ISSN  0028-1050 , pp. 169-175.

Individual evidence

1. ↑ Hochwinter ( Memento of the original from September 9, 2011 in the Internet Archive ) Info: The  archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . In: Weather Lexicon. wetter-suedtirol.net
2. ↑ cf. for example the diagram of snow depths in early winter (November, December), high winter (January, February) and late winter (March, April) at the three stations of Andermatt, Bever and Davos. In: Stephan Bader, Pierre Kunz: Climate Risks - Challenge for Switzerland. Final report NFP 31, vdf Hochschulverlag AG, 1998, ISBN 3-7281-2605-5 , p. 56 ( limited preview in the Google book search);
   Martin Schneebeli: Interactions between climate, avalanches and technical measures. Final report within the framework of the national research program "Climate Change and Natural Disasters" NFP 31, vdf Hochschulverlag AG, 1998, ISBN 3-7281-2604-7 , 3.5 Snow depths in early, high and late winter. P. 46 ff ( limited preview in Google Book search)
3. ↑ H. Flohn, P. Hess: Large weather singularities in the annual weather pattern of Central Europe (= statistical-synoptic investigations 2). In: Meteorological and Hydrological Service of the German Democratic Republic: Meteorologische Rundschau. 2, 1949, pp. 258-263.
4. ↑ for example in Meteorologische Rundschau. 7, 1954, ( limited preview in Google Book Search)
5. ↑ The late winter or also: The "Russian whip" is late! In: DWD: Topic of the Day , February 24, 2018.