Random thought I just had while watching beautiful clouds from my living room window. People before the age of enlightenment had all kinds of myths about things in space and the sky, the sun, moon, stars and planets. But I’ve never heard if there were also magical/mythological explanations for clouds, or did people always understand that they were the same as mist or fog on the ground and made of water? Sure, it’s kind of obvious to deduce a correlation between clouds and rain, but they still hadn’t the chemistry and physics to explain it.
I think any place near water, they’d likely have experienced dense fogs and could have surmised that those were clouds low to the ground.
Then how came the meme about angels sitting on clouds and playing their harps up 
? You can’t sit on fog.
Better yet, anyone who lives on certain mountains sees clouds from above, below, and within, on a regular basis.
It would seem like anyone who took some serious time observing and thinking about it would reach the conclusion that clouds are water vapor pretty quickly.
And yet… the early element theories posited 4 elements: Air, Earth, Fire and Water, without realizing that water could be turned into “air” by applying fire…
Yes, that’s a good point I didn’t take into consideration although I live in the mountains. 
I just had another thought: did ancient people at least do predictions from watching the clouds? I mean, I’ve never understood reading the future from birds’ flight, burned bones or tea leaves, that’s all just so random, but with a bit of imagination you can see all kinds of things in certain cloud formations. Just 10 minutes ago, there was a cloud outside my home that looked like a guinea pig, a much clearer pointer than a crack in a bone.
Agree. There’s a very strong correlation between the presence of rain and the presence of clouds, so it seems like it would be a no-brainer.
And now I have that Joni Mitchell song stuck in my head.
In Disney’s Elemental, the “air” people (creatures? beings?) take the form of clouds - likely because that was the easiest visual shorthand for air.
The Bible associates clouds with water and with fog, but also with smoke and fire because of their relationship with lightning.
Aristotle on clouds:
The exhalation of water is vapour: air condensing into water is cloud. Mist is what is left over when a cloud condenses into water, and is therefore rather a sign of fine weather than of rain; for mist might be called a barren cloud. So we get a circular process that follows the course of the sun.
So he seems to have got it sort of right, even if not completely. And the works of Aristotle were a major component of the mandatory curriculum of all European universities in the Middle Ages and early modern era, so I suppose his ideas were widely supported.
So they knew that water could have a gaseous form, interesting.
I would think that that would be clear to anyone who ever watched a pot of boiling water produce steam, and subsequently decrease in volume.
Yes, but I thought they hadn’t made that connection because they talked about Air and Water as different elements.
Looks like I was underestimating our ancestors, they knew even then that elements could have gaseous and liquid forms, even if they were a bit wrong on their number and precise nature.
Relevant trivia: some people will see a white “cloud” emanating from a water source (e.g. tea kettle, cooling tower) and say, “Ahh, that’s water vapor.” While it does contain water vapor, that’s not what they’re actually seeing. What they’re seeing is a mist. Water vapor is invisible.
Yeah, the water cycle was pretty well known at least by 500 BCE in Greece and probably 200-300BCE in other places. Aristotle pretty much nailed it in Meteorology: “By it [the sun’s] agency the finest and sweetest water is everyday carried up and is dissolved into vapor and rises to the upper regions, where it is condensed again by the cold and so returns to the earth.”.
The main thing they got wrong was assuming that rainfall wasn’t enough to keep the rivers and seas full so there must be some underground source for the rivers (and perhaps some loop back from the seas into those sources).
Cite: Water cycle - Wikipedia
Nearly universal among moderns. We have not gotten any smarter.
Not smarter, but more knowledgeable.
When I was little, I used to stare upwards at the “cotton balls” in the sky.
There’s evidence that humans have gotten more stupid. Crap like this is commonly encountered on social media.
They really don’t know clouds, at all.