Army of Dementors

The evening sky eerily resembles an army of dementors and the trail left by a jet looks like a patronus spell which is keeping the dark army at bay.

Or does it look like hope fleeing from despair?

Dark shadows of despair
Looming behind
Calling out to each other,
gathering,
like an army of dementors
to suck out all joy,
While hope sends a patronus,
A trail shimmering bright
to dissipate 
the army of darkness.