Our speaker is an observer just like us. He's got an active voice that places us right in the front seat as we watch the fog's approach and eventual departure. He speaks in a present tense that makes us feel as if we're in the moment even more. And he's not trying to speak over our heads about anything. He kind of sounds like us, only he's got some poetic chops that provide some awesome metaphors and imagery.
He's also very casual and cool about the whole thing while still managing to capture those different emotions we may feel while watching the fog. So although he's not crying or yelling at us about anything, his coolness adds to the poignancy of his words even more. Sometimes a whisper carries much further than a shout.