The winter solstice is upon us on the 22nd December at 0530 UTC. The solstice marks the point at which the sun reaches its most southerly point in the sky, -23.5 degrees. This latitude is known as the Tropic of Capricorn.
On this day, everywhere above 66.5 degrees north, the Arctic Circle, will be in total darkness. Similarly, places south of -66.5 degrees, inside the Antarctic Circle, will not see the sun set.
The solstice does not have as much meteorological significance as one might expect, given that the sun is the main driving force behind the weather. The main climate zones, which tend to move north and south with the sun, are modified by other factors, primarily ocean currents.
So, for instance, the monsoon season in northern Australia does not usually begin until one to two weeks after the solstice and persists until March, at which time it retreats towards the north.
For those living outside the tropics the solstices, winter and summer, mark the point at which daylight is either at a minimum or a maximum. This can play a big psychological part in determining our perception of the weather.
Short, dark days can cause what are sometimes known as the ‘winter blues’ or even lead to the more serious condition, seasonal affective disorder (SAD), a recognized depressive illness.