However, trails from jet plane is not natural. Many science literature only mention probable life expectancy of trails of under 30 minutes. Trails that has life of hours is never been observed in situ, always from satellite observation. And trails that last for hours never been sampled to my knowledge.
This is example of observation:
On the Transition of Contrails into Cirrus Clouds
Following different jet aircraft during more than 60 occasions, contrails older than about 10–15 min could only be identiﬁed and sampled in very few cases. This raises the question whether very low concentrations of upper-tropospheric ice crystals frequently occur under conditions that are also favorable for contrails to form and persist.
People who often see chemtrails crisscrossing the sky would find this amusing, because they often report many trails last for many hours. Those scientist may never get trails that last for hours if they kept following the plane. Or they would not be allowed to follow.....
Trails of jet plane should never be compared with other natural phenomena. Water is only a part of what jet engine exhaust produce. There are other thing that can alter the way the contrails produced.
ENVIRONMENTAL EFFECTS CIVIL AVIATION, Contrails
Aircraft engines emit water vapor, carbon dioxide (CO2), small amounts of nitrogen oxides (NOx), hydrocarbons, carbon monoxide, sulfur gases, and soot and metal particles formed by the high-temperature combustion of jet fuel during flight. Of these emittants, only water vapor is necessary for contrail formation. Sulfur gases are also of potential interest because they lead to the formation of small particles. Particles suitable for water droplet formation are necessary for contrail formation. Initial contrail particles, however, can either be already present in the atmosphere or formed in the exhaust gas.
Trails from unnatural sources should never be explained by something from natural sources. The explanation from the link above should never be considered real.
What scientist can model is contrails that last for 30 minutes at most. Contrails that last for hours is impossible for them. They can not simulate or explain it using only jet engine exhaust output.
This should bring enough hint that hourly persistent contrails may not be contrails at all.
Also remember that the photos posted on contrailscience website may not be the photos of plane that actually produce trails that last hours. What being shown as what you see, may not be the same thing as what you actually see at all.