Can contrails last for hours and spread out?

Question

i see planes fly overhead and they leave trails that last a long time

Answer 1

Actually the ice particles from the contrail serve as condensation nuclei for other ice particles.

On rare occasions, I've seen a clear sky go overcast (8/8 coverage) after one jet left a con.

Answer 2

Contrails typically last less then a couple of minutes.  If it last longer then it is what they call a chemical trail.  Interesting subject if you want to do some research on it.

Answer 3

Speaking as a "Golden oldie",contrails were a novelty

when we first saw them during WW2.We'd stand in the school playground and watch Allied bombers assemble in huge formations.

Often,their vapour trails would cover a blue summer sky and quite often it'd come on to rain.

Answer 4

If conditions are right - DEFINITELY.

Answer 5

depends how humid the air is

Answer 6

yes

If the air has so much water vapor in it already that it can’t hold any more (i.e. it’s “supersaturated”), then the ice crystals can’t sublimate, and so the contrail will stay around for a long time. The ice crystals might even attract water from the air, if there is enough, and the contrail will get thicker. Winds might make the contrail spread out to even cover the whole sky.