A singularity is a weather phenomenon likely to occur with reasonable regularity around a specific approximate calendar date,
[ Barry R.G. & Chorley R.J. (1987), ''Atmosphere, Weather & Climate'', 5th ed, Routledge, ] outside of more general seasonal weather patterns (e.g., that
May Day
May Day is a European festival of ancient origins marking the beginning of summer, usually celebrated on 1 May, around halfway between the spring equinox and summer solstice. Festivities may also be held the night before, known as May Eve. Tr ...
is usually warmer than
New Year's Day
New Year's Day is a festival observed in most of the world on 1 January, the first day of the year in the modern Gregorian calendar. 1 January is also New Year's Day on the Julian calendar, but this is not the same day as the Gregorian one. Wh ...
in
northern locales). The existence of singularities is disputed, some considering them due to seeing patterns in noise and statistical artifacts from small samples.
In North America, the most significant purported singularities are
January thaw (warmer weather around January 25) and
Indian summer
An Indian summer is a period of unseasonably warm, dry weather that sometimes occurs in autumn in temperate regions of the northern hemisphere. Several sources describe a true Indian summer as not occurring until after the first frost, or more ...
(warmer weather in mid-autumn).
More fanciful ones include the British tradition that rain on
St. Swithun's Day (15 July) will be followed by forty days and nights of rain, and similar folk beliefs around
groundhog day
Groundhog Day ( pdc, Grund'sau dåk, , , ; Nova Scotia: Daks Day) is a popular North American tradition observed in the United States and Canada on February 2. It derives from the Pennsylvania Dutch superstition that if a groundhog emerges f ...
.
Studies
Although folk tales such as St Swithun's Day generally have little credibility, some of these events have a more solid basis. Early scientific investigation involved the creation of calendars of singularities based on temperature and rainfall anomalies. Later and more successful work by
Hubert Lamb
Hubert Horace Lamb (22 September 1913 in Bedford – 28 June 1997 in Holt, Norfolk) was an English climatologist who founded the Climatic Research Unit in 1972 in the School of Environmental Sciences at the University of East Anglia.
Career
...
of the
Climatic Research Unit
The Climatic Research Unit (CRU) is a component of the University of East Anglia and is one of the leading institutions concerned with the study of natural and anthropogenic climate change.
With a staff of some thirty research scientists and s ...
was based on air circulation patterns. Lamb's work analysed daily frequency of airflow categories between 1898 and 1947. Similar work was carried out by
Flohn and Hess in central Europe based on analysis of air flows from 1881 to 1947.
A 1955 study by
Liverpool Observatory and Tidal Institute analysed maximum daily temperatures at a single location from 1900 to 1953. This found problems when attempting to demonstrate the statistical significance of apparent temperature anomalies.
In the 1950s,
E.G. Bowen suggested that some rainfall calendaricities might be explicable in terms of meteoric particles from cometary orbits acting as ice nuclei in terrestrial clouds; his theory received support from a number of sources
However, such work has now fallen out of favour due to modern dynamic modelling techniques, although articles are still being written reflecting an interest in the topic.
References
External links
Singularitiesdeveloped for the
British Isles
The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles (O ...
*
{{DEFAULTSORT:Singularity (Climate)
Climatology