This isn't an answer to the exact question, but the following link is to an image that I thought was worth looking at anyway:
And @justhalf found another image which looks even more like the one in the question, except rotated 90 degrees:
I'm thinking that the actual answer is something to do with
light reflecting off the windows of a high-rise building
but I'm not confident enough of the physics to say that that is definitely the answer.