I think it is exactly what the picture shows. Try this: anytime you see a remarkable trail behind a plane, try to find that plane on

Flightradar24

Live Flight Tracker - Real-Time Flight Tracker Map | Flightradar24

The world’s most popular flight tracker. Track planes in real-time on our flight tracker map and get up-to-date flight status & airport infor...

which tracks all aircraft with a civil transponder. In the majority of cases they don't show on fr24.com . They are military aircraft.