First off check out these tutorials on Weather Replacement by Aharon Rabinowitz.
Here are just a few ideas/things to think of that come to mind, I’m sure others here will have some more thoughts. To put the Arc in the water, make sure you shoot it in a way so that you can remove that tree. Since you are going to have to paint/clone that out.
For the water, you will need some stormy footage that is shot in a perspective similar to how you shoot the Arc(probably best is to find the footage and try to match the perspective). If the shot is shaky, that might actually help as you could use AE’s camera tracker to integrate the Arc into the shot.
You will need to layer the water, masking out the foreground water to put in front of the arc. You probably will want to mask out the arc also to have a water background plate.
Johnny Cuevas, Editor
Thinkck.com
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—THOMAS EDISON on inventing the light bulb.