"Day graciously agreed to examine photographs of chemtrails to see if he spotted anything unusual. 'This is a perfectly normal situation with cirrocumulus cloud and a single spreading contrail,' he declared after inspecting one photo for a full minute."
The problem is, it is not possible to differentiate between contrails and chemtrail from just a photos. You need video or atleast information of duration.
"The criss-cross pattern is a consequence of planes flying criss-cross patterns....' And the next. 'I've seen many situations like this one....'"
Seeing many do not means that it is a natural phenomena.
"Contrail formation, Day explained, depends on the relative humidity of the atmosphere-- he ratio of what is to what could be at a particular temperature. When relative humidity is low, contrails dissipate within seconds. But when relative humidity is high, especially at the subzerotemperatures of the upper atmosphere, the addition of even a tiny amount of water vapor acts as a catalyst. Under these conditions, contrails may linger and spread to cover the whole sky."
That is true, but it is very questionable that the condition require would happen often. Scientist mention that it rarely to happen.
"At length, Day extracted from his bookshelf a well-thumbed edition of Peterson's Field Guide to Clouds and Weather, which he co-authored in 1991 (a good 10 years before chemtrails became widely discussed), turned to the section on contrails, and pointed to a photograph of a thick, white plume--a plume that looked for all the world like a chemtrail"
Exactly, we can not tell the difference of contrails and chemtrail from just photos. And no one can tell if the photos is actually chemtrail or contrails without more data.