A still, dark November night lies over the grey, concrete University campus. Hanna is sleeping softly, breathing slowly and deeply, her forehead wedged against the keyboard of her laptop. Its blue-white light pulses over her long brown hair.
I can't help feeling this exercise is a bit unfair on me. The fourth sentence explains a lot!
It often does.
But the rules, you know...
I'm not one to shy away from using adjectives and adverbs when they enhance the writing, but in this case, I think you have too many. For one thing, it sets up an undesirable, sing-songy rhythm if you're always pairing the adjectives: still dark, gray concrete, blue white, long brown. We probably don't need to know how Hannah is sleeping, only that she is. Night is always some form of dark and is often still, and I don't know why we need that information anyway. Concrete is usually gray, so that's another unnecessary descriptor.
OK, so on to the content. This is omniscient voice and pure description. Nothing wrong with either one, but if this is going to involve Hannah waking up in the next sentence or three, then that could be a problem, as the waking-up opening is probably the most common opening employed by unpublished writers. That's not to say you can't ever do it--and certainly published writers have--but it's got to be different and compelling.
Anyway, the overwriting in this one would not entice me to keep reading, and the fact that the character is asleep is another mark against it. Would happily look at a revision, though, if you decide to do one.