gnome said:
...that suspicious lump. .
Here's the picture with the so called lump:
The anomaly has two distinct properties. A short horizontal line from one shoulder to the next. And and a long slender line from the same point at about the top middle of his back, all the way down to the tail of the suit. These two lines are perpendicular to each, or rather at right angles to each other.
If you look at the vertical line as compared to his shoulders, you can clearly make the judgement that it is approximately center with his back, along the same axis as the backbone, or vertebrae.
These lines form a "T" shape rather than a square that some people are inferring.
The small horizonatal wrinkle corresponds from point to point with the bottom part of the shoulder blades where there is somewhat of a blunt rounded point on the bone itself. Reach around your back to your own shoulder blade and you can feel it.
Now look at the posture of the President and you can clearly see that his shoulders are exerting force outwards, pulling on the fabric of the suit and in effect pulling it tight and smooth directly above that point and forming the outline of the bone of the shoulder blade.
Below all this, there is nothing exerting equal lateral force like there is above, so it won't have the same tension here and thus the fabric in this area won't be smooth. Now if we look at the President's posture again we clearly see that he is somewhat hunched forward and his head is not in line with his vertebrae, and this force that is pushing forward and perpendicular to the lateral force of the shoulder blades, has the effect of pulling up on the suit, causing the fabric in the area below the shoulder blades that is free of lateral tension to form the wrinkle that you are seeing.
The vectors of the wrinkles correspond to the tensional forces that are being applied ...it is that simple.
A well tailored suit, probably enhances the effect since there is less material to absorb the tensional forces generated by someone who is very animated like the President...and especially with his physique of large shoulders.