The blue hour phenomenon can be seen all around the world, but it seems to be most beautiful the further north you go. It's the period of twilight before real daylight starts, well before the sun can be seen in the sky.
In Tromsø the blue hour is the only light they get at this time of year, lasting several hours before the darkness returns. Here in Trondheim we've had some gorgeous (if a little chilly!) mornings lately.
Here's a selection of snaps from my morning commute (walk!) down from Moholt to the city centre: