sky vs. skies

[sagehen]

For this native English speaker, "sky" is what encloses the horizons where
I am.  "Skies" are like landscapes, they are everywhere, including here.
Looking up, I see an airplane in the sky, but when I am flying, I don't
feel myself to be in the sky, but merely in one of the layers of the
earth's atmosphere. Getting back to the original question:   "Why 'the
skies' but not 'the sky' in the following sentence: 'And that's without
having to see the rubble or listen to the fighter jets patrolling the
skies?'"  while it could be either, "skies"  somehow satisfies the image of
various overlapping skies over Manhattan, over the Hudson, over New Jersey,
over the East River, over Long Island that would all be within the prowl of
the jets.
A. Murie