From Day to Night

When it get's dark in Hong Kong it get's dark fast. It's one of the things I like most about coming home from work on a Saturday evening. Every time you look up into the sky it is a different colour, a darker shade of blue. I managed to capture a small  hint of the speed of this change in two pictures as I crossed a footbridge to get home:

All I did from one photo to the next was walk from one side of the footbridge to the other. Oh the speed of light.