What Happened to All the Airliner Contrails?

I’ve seen plenty of airliners flying overhead this past week, but not a single contrail. Did the government mind control program conclude successfully? Or has the singularity already occurred and the master AIs forgot to draw contrails? —Bunker Man

When you’re feeling overwhelmed by all the willful ignorance and stupidity in today’s world, sometimes it helps to stop and appreciate all the stupidity from yesterday’s world that’s not around anymore. Think about it: When was the last time you ate a Tide Pod? Seen any good planking videos lately? Ever wonder what Justin Bieber’s up to these days?

I say this, Bunker, because your letter—touching as it does on one of the bigger conspiracy theories of the 2010s—has reminded me that, as shitty as it is that at this very moment there are actual adults who think Bill Gates invented COVID (though I can see how people might decide that the guy who brought Clippy into the world could be capable of anything), at least we haven’t heard much about chemtrails for a while.

Ironically, it’s precisely the phenomenon you describe—sometimes planes leave contrails in their wake, sometimes they don’t—that inspired the whole theory that [choose your favorite nefarious entity] was using commercial jets to secretly spray Americans with [insert dangerous chemical here] in order to further the goal of [vague but unspeakably evil plan].

What gets me about this theory is that it assumes the perpetrators are smart enough to mastermind a conspiracy requiring hundreds of thousands of participants (and keep it a secret!), but not smart enough to just spray plain water from any non-poison-packing flights so the rubes won’t notice the inconsistency.

In real life, they’re spraying plain water every time. Jet exhaust—like a car’s tailpipe emissions, or your breath—contains water vapor. Sometimes, depending on ambient temperature and humidity, water vapor may condense into tiny droplets and make a visible cloud. Other times it may not. Apparently, atmospheric conditions in your neck of the woods last week favored “not.”

This, in a nutshell, is the reason that contrails are fickle. It’s the same reason that you can see people’s exhaled clouds of breath outside in winter but not in summer, and most people seem capable of accepting that at face value. (Though if you insist on blaming a secret, seasonal, outdoor-only fentanyl-smoking conspiracy, I suppose I can’t stop you.)

Questions? Send them to dr.know@wweek.com.