this post was submitted on 10 May 2025
1344 points (98.8% liked)
memes
14715 readers
3262 users here now
Community rules
1. Be civil
No trolling, bigotry or other insulting / annoying behaviour
2. No politics
This is non-politics community. For political memes please go to [email protected]
3. No recent reposts
Check for reposts when posting a meme, you can only repost after 1 month
4. No bots
No bots without the express approval of the mods or the admins
5. No Spam/Ads
No advertisements or spam. This is an instance rule and the only way to live.
A collection of some classic Lemmy memes for your enjoyment
Sister communities
- [email protected] : Star Trek memes, chat and shitposts
- [email protected] : Lemmy Shitposts, anything and everything goes.
- [email protected] : Linux themed memes
- [email protected] : for those who love comic stories.
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Incorrect. The condensation you are seeing in the air is a product of combustion. If no water was added to the air, then compressing it and decompressing it would not create a cloud or vapor trail.
Edit: Fine. It's mostly incorrect.
https://en.wikipedia.org/wiki/Contrail
Yes, the lower pressure can create a very temporary contrail, and in rare situations where the engine exhaust also cools down below freezing before it reaches ambient pressure, ice crystals can form and create a longer more visible contrails. Realistically, what you are seeing in a contrail is water vapor from combustion. Seriously, H2O and water are the largest products of combustion, and it's like 99% of what you are seeing behind aircraft.
The longetivity of a contrail is determined by the atmospheric conditions. In sufficiently dry air no contrail is formed as the water introduced by the combustion isn't enough to raise the frost point to the ambient temperature. More humidity means that the contrail may form and even persist for a while without sublimating away (Cirrus homogenitus). If the air is even more humid, the contrail may even start to grow and change shape (turning into Cirrus homomutatus). This last case is what I suspect gets the foil hats most riled up about "chemtrails".
https://cloudatlas.wmo.int/en/explanatory-remarks-and-special-clouds-cirrus.html