Wednesday, October 6, 2010
winter season is just around the corner
Astronomically, the winter solstice, being the day of the year which has fewest hours of daylight, ought to be the middle of the season, but temperature lag means that the coldest period normally follows the solstice, so the season is sometimes regarded (in the USA and Britain) as beginning at the solstice and ending on the following equinox.
In the Northern Hemisphere, depending on the year, this corresponds to the period between 21 or 22 December and 20 or 21 March . Meteorologists in the UK consider winter to be the three coldest months of December, January and February. In Scandinavia, winter traditionally begins on 14 October and ends on the last day of February.
In many countries in the Southern Hemisphere, including Australia, New Zealand and South Africa, winter begins on 1 June and ends on 31 August. In Brazil the winter begins on June 21 and ends on September 23.
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 1 November, on All Hallows, or Samhain. Winter ends and spring begins on Imbolc, or Candlemas, which is 1 or 2 February .
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 through July in the Southern Hemisphere.)