Saturday, April 9, 2016

Winter 2015 : WINTER and winter solstice

First entry on our experiences during winter in the Manchester.
Let's learn about winter!

From the Met Office:

When does winter start?

The day in our calendar that marks the first day of winter usually refers to the astronomical seasons which are a result of the Earth's axis and orbit around the sun. However, at the Met Office we often use a meteorological definition of the seasons. Let's take a brief overview of the difference.How you define the first day of winter depends on whether you are referring to the astronomical or meteorological winter.
Meteorological and astronomical seasons
Astronomical seasons are relative to the position of the Earth's orbit around the sun taking into account equinoxes and solstices. Meteorological seasons are instead based on annual temperature cycles measuring the meteorological state and coinciding with the Gregorian calendar to determine a clear transition and equal length of season.

Meteorological winter season

This year the meteorological winter began on 1 December 2015 and will end on 29 February 2016.
The meteorological seasons consists of splitting the seasons into four periods made up of three months each. These seasons are split to coincide with our Gregorian calendar making it easier for meteorological observing and forecasting to compare seasonal and monthly statistics. By the meteorological calendar, winter always starts on 1 December.
The seasons are defined as Spring (March, April, May), Summer (June, July, August), Autumn(September, October, November) and Winter (December, January, February).

Astronomical winter season

This year the astronomical winter begins on 22 December 2015 and ends on 20 March 2016.
The astronomical calendar determines the seasons due to the 23.5 degree tilt of the Earth's rotational axis in relation to its orbit around the sun (winter solstice). Both equinoxes and solstices are related to the Earth's orbit around the sun (more here).

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