Lovely image of one of my favourite views. Have a 5 for the nostalgia. However, the sky looks odd. Is this a single image?

Thanks for the compliment. Yes, it is a single image, though I must admit to intensifying the cyan a bit, as the sky was a bit weak. Maybe that's what you're seeing.

Have you ever noticed the deep purple colour of the new twig growth on birch trees in the winter? It's one of the nicest features of this picture.