What was the rejection reason? Technical issues?
No focus, a lot of artefacts
And a histogram that is highly missing blacks, shadows, part of the exposure range and whites.
FYI: you should have, for a well exposed picture, information from the left to the right, with no flat line.
Zoom in between 100-200% and the colorful, purplish artifacts become very apparent. This is a feature of a small sensor (mobile camera phone perhaps?). I wouldn't waste any time submitting images of clouds or skies. If you query the database for "clouds" you will see that there are already more than 21 million in the database. Though Adobe would probably accept yours if it were technically perfect, the chances of ever selling it are infinitesimal.
Technical issues aside, if there was something interesting in the sky it would have a lot more commercial appeal. Hot air balloons, kites, skydivers, birds, UFOs, something to draw viewer's eye into the scene.