Well,.. I would have to say that the last month here has been unusually good for this time of year. Generally nice and sunny and around 21 degrease multigrade.
But not as nice as nth Qld. I will admit that.
The photo you put up is a classic condensation trail. Nothing more.
Condensation trails can actually get larger with time because the condensed particles can act as a seeding agent for other water vapour in the atmosphere.
It is unusual but when conditions are exactly right, it does happen.
Because there are so many aircraft up there now, what used to be highly unusual is now becoming more common.
As far as the make up of the trail goes, it's not just pure water vapour. There are the by-products of the combustion of kerosene in the condensation trail, so to be technically correct, I suppose it could be termed a chem trail. But the suggestion that there are government or Illuminati sponsored aircraft flying around "gassing the masses, we're kicking asses, but we dont tell why" (to use an expression from the Chemtrailarrillion club song

), the suggestion is laughable.
Almost as laughable as the Chemtrailarrillion club rally song

I can't help myself. here it is again. sing along everyone,..
Chemtrailarrillion we have a million
planes up in the sky
gassing the masses, we're kicking asses
but we dont tell why
C
Because we can keep a secret
conspiracys our game
We rule the earth
for what it's worth
by using chemical rain
(copyright Richiefish june 2010)