Hi everyone, and especially Vindog who has the courage to enter the devils' den, so to speak, and actually debate Chemtrails. This is a trait that's pretty rare among chemtrail believers, in my experience anyway. In my adventures in youtube comments, the replies have so far mostly consisted of calling me a paid government shill (the default canard thrown at anyone who doesn't immediately believe in chemtrails, it seems) and a lot lot worse.
Anyway.. I just wanted to ask Vindog a few questions, and hopefully he'll still find the time to provide a reply.
1- Describe what a contrail is. How does it form, what circumstances are involved? You've hinted that you do believe that contrails can sometimes persist, so under what circumstances would that happen, and how often do you think these circumstances occur?
2- I think you know what a cirrus cloud is. Still just some questions, so we can arrive at my point. What is a cirrus cloud, at what altitudes do we find them, and what do they consist of?
3- And finally, in what way is a cirrus cloud different from a persisitent contrail?
And just to help you out a bit, I'd like to provide a couple of youtube clips.
First a clip of someone spraying hot water in freezing air (-42C). What you see happening in the clip is how the water freezes almost instantly and becomes an ice cloud of sorts.
Now imagine a jet taking of in the same circumstances. It's jet engines produce mainly H2O and CO2 as they burn fuel (1.3 litres of water per 1 litre of fuel, apprx). In effect those jet engines are spraying hot water vapor, not unlike the gun in the previous clip. So if the circumstances are similar to what you just saw in the previous clip, what do you think happens?
have a look here. This a a jet taking off in -45C:
See any similarity?
Now if you realize that the temperature at 30.000 ft alt is usually around -50C (or lower) then it shouldn't be a surprise that we see the phenomenae we've seen in those clips happen quite regularly. There's more involved than just low temperatures though.. things like relative humidity and whatnot, but at least this gives an idea of what persistent contrails are.
of course there's a lot more to answer.. stuff like all the patterns you've shown in the pictures you've posted, but I think some pretty good explanations for those have been provided here and in other places on this site already. But if you still have questions, feel free to ask
btw in my eagerness to explain I seem to have answered above questions for the most part already.. but still, give it a go