Those streams of 'white' trailing smoke from Commercial Jets in Blue Sky...Vortices?
I was taking a stroll in an park with a female friend close (a rare break from the ATPL). The park was close to City Airport.
There was clear blue sky when looking at 2 passing Jets - there was a trail of white I can only describe as 'white smoke' trailing from behind the jets.
There was a third jet that passed and there was no 'white smoke' - knowing that I am seeking a career in commercial aviation - the female friend quipped 'What is the trailing smoke behind the 2 jets and why is there none on the third passing jet?'
My immediate thought process lead me to believe these may be wing tip and/trailing edge vortices? Which I gave a suitably educated guess at the time.
As I have just done the Chapter on Aircraft Axis and Spanwise Flow - I am still thinking they are tip vortices
Would I be correct or could it also have been something else?
Ta!