Physicians have anti-vaxxers, astrophysicists have Planet Niribu, and atmospheric scientists? We have chemtrail conspiracy theorists whose argument basically boils down to, "I saw something funny in the sky and it is a secret government experiment, that's what youtube says."
As atmospheric scientists, we know there are amazing things up there in the sky that occur entirely naturally as a result of the laws of physics! Here are some of my favourites: (thread - please add yours!)
There is a the "Weird Cloud Atlas" that helps you decipher between Kelvin-Helmholtz waves, mammatus clouds, and the bizarre "morning glory" stripes that only occur over Australia: smithsonianmag.com/smart-news/ufo… 
Then there are all the optical phenomena, caused by light refracting through clouds and ice and water droplets and more: rainbows, sun dogs, halos, etc! (thanks @NASA for all the amazing photos)
Of course humans are affecting what we see in the atmosphere, too. There's plain old boring air pollution, which is responsible for some spectacular smog as well as millions of deaths each year, 200k in the US alone. This is Almaty, Kazakhstan:
* I say "boring" because, in comparison, believing in a secret military experiment is much more compelling. In reality air pollution is a very serious health issue that needs to be taken seriously by nearly everyone, everywhere. See: bbc.com/news/science-e…
Then there are the legit scientific experiments, like the super-high elevation clouds that these NASA rockets generated to track winds in the upper atmosphere: nasa.gov/mission_pages/…
And last but not least, yes: geoengineering is a real thing. But it is not a secret worldwide government plot. Old-school cloud seeding is still done in a few places like here in West Texas and apparently Wyoming, too. It affects *local* precipitation: trib.com/news/state-and…
And scientists like @DKeithClimate are planning to run very small expts to understand the potential impacts of solar radiation management on climate -- before anyone tries to implement them at scale! See: technologyreview.com/s/603974/harva…
If you'd like to know more about what is real and what is not, when it comes to geoengineering, chemtrails, cloud seeding, and what we see up there in the sky, here's our Global Weirding episode on it! Give it a watch:
And if you'd like to know more about condensation trails, or contrails, that result from perfectly normal airplanes but can look extremely weird (no military experiments or strange chemicals needed), check out this great review, with pictures, from @NASA: science-edu.larc.nasa.gov/contrail-edu/c…
