Well, I have had 2 minute storms but also had one that lasted 30 minutes! Sun coming up in the West....lol, hadnt noticed. But time only passing when ya move is....a little silly. Still..SICKNESS game.
I noticed this aswell. When I was doing my very last radio tower unlock I was waiting on the top for the sun to come up, so I could see the little cutscene one more time in daylight. I sat there for 10 minutes and noticed the moon never moved. Then when I looked away and shot some guys with my sniper the moon had suddenly moved across half the sky. I'm guessing it's to lengthen the nighttime when you are sneaking to enhance the tension.