Yes Con(densation) trails is from water vapor...when you see this, the trail dissipates, and does not return.
Chem trails is another story.
Watch and see if the trail in the early morning isn't visible for as far as the horizon. It will fade a little as it widens and if there is enough moisture in the air, a cloud will form.
Rather than reduce the use of fossil fuels and reduce climate change, lets just monkey with it some more.
This at the most benign, is "cloud seeding". Silver nitrate is extremely hydrophylic and if moisture is in the atmosphere, a cloud will form...shading the sun, cooling the Earth.
The state of Texas is openly doing this and charging counties something like 12 cents per square mile or acre?
Anyway some believe that it is more sinister and the pseudo-secret cloud seeding operation is a cover up for something much worse.
I have seen the clouds form from trails that do not dissipate over the inland empire in socal....near March air base.
In mid August I was in NE California looking at land. It was 112 degrees in Redding, and 102 where I was East of there at 5000 feet. (edit:this is unusually hot, and night time lows are in the 40's at elevation, and my daughter and I camped one night) I woke up feezing my ass off and got out of the tent and made a fire (later found out was illegal, though left fire cold!) I was up around sunrise and watched as planes flew back and forth from the direction of Travis Air base and towards the lightly populated areas of Eastern Oregon, Northern Idaho and N. Western Montana???
The air was EXTREMELY dry and hot. The trails widened into strips of very thin clouds that stayed all day. The patterns are not checker board, but somewhat random criss-cross.
The socal ones produced clouds, verga and light rain...and 79 degree days in the high-desert in the first week of August, when it should be 105!
Incidentally, though there may be a good reason, like it's usage in electronics, but silver has become quite rare recently....
Make no mistake, vapor trails dissipate even in the humid mid-western air of my youth, but especially in the arid high pressure dominated West!
I try not to think about this stuff cuz it freaks me out.