can you explain why science doesn’t support the assertion that when water vapor is ejected into ambient temperatures well below zero it will freeze into ice crystals…and if it is humid enough the ice crystals will persist.

What is the scientific rationale that says that is not possible?

“spraying — SNIP — world”

That’s better – but still wrong and thoroughly debunked.
Find out about the technical nature of Air Traffic Control and how it deals with 87,000 daily overflights of the United States. Read its history. Find out how many employees it has.
Then ask yourself why there aren’t ANY “whistleblowers”.
None.
There would HAVE to be, if “secret fleets” of unmarked planes were roaring around at low level they would eventually COLLIDE with VFR aircraft – private low-flying planes. There have been NO such crashes.
None.
Engines spray WATER to make trails – which turn to cirrus clouds, or evaporate, depending on the ambient humidity.
Learn some physics.

Ah, some misunderstanding here it seems

On your part, total. On mine, not at all.

THE DRAGON IN MY GARAGE – by Carl Sagan: “A fire-breathing dragon lives in my garage”

Suppose I seriously make such an assertion to you. Surely you’d want to check it out, see for yourself. There have been innumerable stories of dragons over the centuries, but no real evidence. What an opportunity!
“Show me,” you say. I lead you to my garage. You look inside and see a ladder, empty paint cans, an old tricycle — but no dragon.
“Where’s the dragon?” you ask.
“Oh, she’s right here,” I reply, waving vaguely. “I neglected to mention that she’s an invisible dragon.”
You propose spreading flour on the floor of the garage to capture the dragon’s footprints.
“Good idea,” I say, “but this dragon floats in the air.”
Then you’ll use an infrared sensor to detect the invisible fire.
“Good idea, but the invisible fire is also heatless.”
You’ll spray-paint the dragon and make her visible.
“Good idea, but she’s an incorporeal dragon and the paint won’t stick.” And so on. I counter every physical test you propose with a special explanation of why it won’t work.
Now, what’s the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there’s no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists?
Your inability to invalidate my hypothesis is not at all the same thing as proving it true. Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder.
What I’m asking you to do comes down to believing, in the absence of evidence, on my say-so.
The only thing you’ve really learned from my insistence that there’s a dragon in my garage is that something funny is going on inside my head.
You’d wonder, if no physical tests apply, what convinced me. The possibility that it was a dream or a hallucination would certainly enter your mind. But then, why am I taking it so seriously? Maybe I need help. At the least, maybe I’ve seriously underestimated human fallibility.
Imagine that, despite none of the tests being successful, you wish to be scrupulously open-minded. So you don’t outright reject the notion that there’s a fire-breathing dragon in my garage. You merely put it on hold. Present evidence is strongly against it, but if a new body of data emerge you’re prepared to examine it and see if it convinces you. Surely it’s unfair of me to be offended at not being believed; or to criticize you for being stodgy and unimaginative — merely because you rendered the Scottish verdict of “not proven.”
Imagine that things had gone otherwise. The dragon is invisible, all right, but footprints are being made in the flour as you watch. Your infrared detector reads off-scale. The spray paint reveals a jagged crest bobbing in the air before you. No matter how skeptical you might have been about the existence of dragons — to say nothing about invisible ones — you must now acknowledge that there’s something here, and that in a preliminary way it’s consistent with an invisible, fire-breathing dragon.
Now another scenario: Suppose it’s not just me. Suppose that several people of your acquaintance, including people who you’re pretty sure don’t know each other, all tell you that they have dragons in their garages — but in every case the evidence is maddeningly elusive. All of us admit we’re disturbed at being gripped by so odd a conviction so ill-supported by the physical evidence. None of us is a lunatic. We speculate about what it would mean if invisible dragons were really hiding out in garages all over the world, with us humans just catching on. I’d rather it not be true, I tell you. But maybe all those ancient European and Chinese myths about dragons weren’t myths at all.
Gratifyingly, some dragon-size footprints in the flour are now reported. But they’re never made when a skeptic is looking. An alternative explanation presents itself. On close examination it seems clear that the footprints could have been faked. Another dragon enthusiast shows up with a burnt finger and attributes it to a rare physical manifestation of the dragon’s fiery breath. But again, other possibilities exist. We understand that there are other ways to burn fingers besides the breath of invisible dragons. Such “evidence” — no matter how important the dragon advocates consider it — is far from compelling.
Once again, the only sensible approach is tentatively to reject the dragon hypothesis, to be open to future physical data, and to wonder what the cause might be that so many apparently sane and sober people share the same strange delusion.

This might jog your memory, unless you really don’t read much. (Thanks, Suntour.)

Go find some evidence for your “invisible dragon”, and teach me a thing or two.

*JazzRoc:
**TimeForBed:

**I see now how that has been cleverly achieved to hide the current bout of secret testing in plain sight, as they say. Very clever these secret government types, I guess there may be some page on wikipedia that explains it all in a bit more detail in about 50 to 75 years or so. Maybe an article tucked innocuously into the middle pages of the Guardian.
*Maybe hundreds of scientific research papers that have quantified it, explained it, and made predictions about it over half a century.

- Ah, now, I see why you have misunderstood me here, you seem to have accidentally removed the start of my statement, I’ll just reproduce it here for you, ahem

**Yes, interesting, so “chemtrails” look and behave exactly like contrails.

- Ok, now it becomes clear, so your assertion that there are

*Maybe hundreds of scientific research papers that have quantified it, explained it, and made predictions about it over half a century.

- Is now missing the point by referring as it does to an “it” that I can see equates in your mind to contrails, whereas my statement referred to a secret plan to disguise chemtrails as contrails, you see, for which there exist no scientific research papers at all. Don’t try looking for them to prove your point either because by definition, of course, they wouldn’t be allowed in the public domain.

**Can’t wait to read it.
*That’s strange, for you have read and understood none of it so far. What’s new?

- Ah! Another misunderstanding that may now be clear from my explanation above. There is no scientific research to read and understand on this proposed secret plan. If there was, it would of course be suppressed.

**Until then, don’t talk about the weather!
*No, please talk about it. How much do you know about it?

- This, you see, is just a little ironic joke referring to the well known chemtrail film of the same name. Ha! Yes I don’t actually want to “talk about the weather”… so don’t fret.

**oh yes, I wonder if secret government undercover agents look and behave exactly like ordinary citizens…
*That’s exactly what I wonder about paranoid chemtrailers…

- That’s a rather odd thing to wonder, as a paranoid chemttrailer is an ordinary citizen… unless you are suggesting that a paranoid chemtrailer could be a kind of “double agent” actually working for the secret government to disrupt the chemtrail movement… yes, interesting, I can see how your mind is working here, I’m impressed. Sounds like you know quite a bit about this sort of thing?

Anyway, hope that’s cleared it up for you, have fun!