Notice that the series was that picture "3" was taken before "2" if the flight path was from North to South. Look at multiple depths of the clouds in the background to confirm this. That means that it is a countdown from "3" to "2" and we still have not seen "1" and possibly "0". Also, note that if it is Hong Kong and a flight from North to South, that means that the jet was moving toward the left. That means this will be a "dark to light" since the sunshine is brighter on the left!