These so-called “chemtrails” are just vapor trails/contrails from aircraft. And they can form surprisingly low. I read somewhere about an instance in Hawaii where local conditions were perfect for their formation and they were forming as soon as airplanes lifted off, meaning you had contrails starting roughly at ground level and continuing upwards. If I can find a cite I’ll post it.
As for the criss-crossing and circling… airplanes can’t park. If they need to wait to enter an airspace they do it by flying in circles. It is not unusual for them to be told to circle above a designated point on the ground - thereby freaking out the tinfoil hat types below when really it’s nothing to do with them. Saying “Circle over the lake” or “circle over the stadium with the white roof” provides an easier visual cue to a pilot on a sunny day than saying “circle over a point marked by lat XXXX and long XXXX” even if they do have GPS on board.
As for “unusual locations” - well, there could be a variety of reasons for that they average ground-pounder is unaware of. For instance, while in my area winds are usually west-to-east, a period of wind from, say, due north or east-to-west or due south can required a change in traffic patterns at an airport so airplanes will use a runway more in line with current wind conditions. This means, of course, their approach to a landing will be different than usual which can generate contrails in other than the expected places. Nothing sinister about that. in fact, the rationale here is increased safety.
Another reason might have to do with radar, or lack of it. I’ve been airborne once or twice when the radar system over Chicago has gone down and, to increase safety, air traffic control will spread out the traffic which means airplanes in unexpected locations. And while they’re sorting all that out they may well stack 'em up in convenient locations which, again, means circles over unexpected locations and much consternation among conspiracy theorists.
And, finally, there are “TFR’s” or “temporary flight restrictions” that pop up these days for many reasons, among them around presidential parties, major league ball games, and due to hysterical city mayors. This sets a large area of sky “off-limits” to airplanes (size, shape, and height varies) and while they affect jets less than smaller planes, they, too, can result in air traffic being shifted to areas it’s not normally seen, or many more planes than normal traveling over a certain area. If someone “busts” the no fly zone you will, these days, get jets in pursuit, meaning you’ll see them where normally you don’t.
Note that among these chemtrail enthusiasts you never get a pilot. Why? Because pilots know 99.99% of this is weehocky. They understand changing traffic patterns and holding patterns without needing to subscribe to whacked-out conspiracy theories. Airplane exhaust and the occassional blue ice bomb - well, I guess that is “weehocky” of a sort - aren’t good for you, but unless you’re directly behind a running jet engine you’re unlikely to get enough exhaust (or heat) to kill you, and the blue ice - that’s strictly a wrong-place-at-the-wrong-time thing. Heck, a group of tourists on a Chicago boat tour got doused with something similar from one of the Dave Matthew’s Band tour bus recently while going under a bridge so it’s not like eliminating airplanes will totally eliminate that hazard.