
The
season with the shortest days and the lowest average temperatures,
winter astronomically begins on the winter solstice (when
the tilt of the Earth's axis is most oriented away from
the Sun) and ends on the vernal equinox (when the tilt of
the Earth's axis is oriented neither from nor to the Sun
causing the Sun to be located vertically above a point on
the equator). The winter solstice occurs between December
20 and December 23 in the Northern Hemisphere and between
June 20 and June 23 in the Southern Hemisphere. The vernal
equinox ending winter occurs on March 20 or 21 in the Northern
Hemisphere and September 22 or 23 in the Southern Hemisphere.
Meteorological
winter is the season having the shortest days and the lowest
temperatures. The coldest average temperatures of winter
are usually experienced in January in the Northern Hemisphere
and in July in the Southern Hemisphere. In other words,
New York City experiences winter in January and Buenos Aires
in July.
The
lowest winter temperature ever recorded was -128.6 F on
July 21, 1983 at the Russian research station located near
the South Pole at Vostok, Antarctica. In the Northern Hemisphere,
the Siberian towns of Verkhoyansk and Omyakon frequently
record -90 F in January and February. Please note that all
of these frigid temperatures do not include a wind chill
factor.
Traditional
winter begins and ends in many nations and cultures differently.
In Celtic nations such as Ireland using the Irish calendar
and in Scandinavia, the winter solstice is traditionally
considered as midwinter, with the winter season beginning
November 1 on All Hallows or Samhain. Winter ends and spring
begins on Imbolc or Candlemas, which is February 1 or February
2. This system of seasons is based on the length of days
exclusively. The three-month period of the shortest days
and weakest solar radiation occurs during November, December
and January in the Northern Hemisphere and May-July in the
Southern Hemisphere. Also many mainland European countries
tend to recognize St. Martin's day (November 11) as the
first calendar day of winter. In Chinese astronomy (and
other East Asian calendars) winter is taken to commence
around November 7.
In
ancient China, winter was known as Black Tortoise.