My first day at work in 2014. It always seems darker going back after Christmas. I always though that it was just psychological after getting up in the light for a couple of weeks. In fact, if you look at the sunrise times, the sunrise gets later and later for a couple of weeks after the solstice. The days do lengthen because sunset time drifts out even more. The reasoning is to do with the tilt of the Earth and the fact that the Earth spins on its axis whilst also moving round the Sun. I'm working on a sensible explanation - maybe by next year!
