Opposite what? Light and dark? Hmm...

I'm also not sure that the black shape helps the composition any. Nice tone in the clouds, but I'm just not sure about this one.

Another shot in which I wish the author could describe what they saw here....

Well done! I really like this one. I can't quite say what the opposites are, but I definitely see them. Hard and dark geometric shapes versus light and fluffy colorful shapes... something like that!

And I like the overall composition, with the diagonal of the top of the building (or wall or whatever it is). I even feel like the top cloud creates a diagonal, though I'm sure it's helped by the effect of the wall. Pretty cool.