I have completed a recording section, unfortunately before seeing the concept, but there are enough details on it to get you in the road to this effect. Once the video is edited (because there are so many interruptions when we want to record one, lol) I will sit and think in a math model mixed with noise to achieve this and the mask, but it is very important that you watch the videos and study the materials I have shown to understand where the things are.
One particular problem with the concept above is that you can’t tell precisely where the main light source is coming from since the tower is not casting any shadow and also there are too many lit edges at the lower left portion of that picture that would tell the light source is coming from above while passing through the clouds that even not been seen from the top, looks like they are disposed as rings (as an onion) with some certain distance between each shell.
Stay tuned for the video, hopefully released late today or tomorrow morning (we are GMT -3 currently).
Cheers!
PS: due to holidays and to bring a very detailed video we might actually release it on the following week.