This is not only a stunning image, but a stunning exposure as well!
You have explained before that you meter the critical part and then take your individual shots across the panorama in manual exposure mode based on the critical section. This shot has a direct shot into the sun as well as the pan of the clouds; I would expect the direct sun shot to be a very different exposure. (I seem to always mess these up.) I'm also amazed by how you can shoot 13 (or however many) exposures in such a short time that the exposure values don't change from the first to the last. You are incredible!