reply to post by woodwardjnr
Contrails have always 'behaved' the same...with the proviso that more modern high-bypass turbofan engines tend to produce more long-lasting
contrails. ALSO, it depends entirely on the relative humidity in the airmass at the moment the contrail is formed. Just as clouds don't form in
very dry air, or form and evaporate quickly. Watch some time-lapsed videos of clouds, you can see them form and evaporate...
Here's one example....clouds. But, a contrail is really just an artificially formed cloud...
The OP's photo is artfull...looks like the Moon illuminating the contrails. AND you can plainly see they
are contrails, as one passes over
the other. They were formed at different altitudes.