It looks to me as if much or all of the smoke may have been photoshopped in. Some of the buildings in the left background look odd, as well.
First, the plume of smoke on the left. The smoke is not consistent in the lower portions. Where the buildings show through the plume, there are just no pixels of smoke there at all, but the smoke is thick right beside the buildings. The clone stamp tool is so obvious in the upper portions.
Next, the smoke plume on the right. The lower portions are properly fuzzy, but in the upper portions, there are large square areas in the middle of the plume. That is an indication that at least that portion of the plume was added to the photo.
There are odd square pixel formations in the middle plume as well, primarily in the base.
The square areas could be JPEG compression artifacts. But that wouldn't explain the pattern of the smoke eddies at the top.