Picture posting is enabled for all :)
It is in winter because this is when the pagan festivals are. Solstice is of course on 21st December and the celebration is that things get better from hereon so lets have a nice cheery festival during these dark days. The Romans had there mid-winter festival actually on 25th December and it is this pagan date that the Christians nicked - it was the only way of getting the pagan locals on board.
Originally it was January 6th (and still is in Holland) but I don't why on that one!
And there is also a Rolf Harris song about Santa's sleigh being pulled in the southern hemisphere by 6 white kangaroos!