But consider an alternative. What if the surface was inhospitable to life and likewise the shallow regions of the ocean were likewise.
Imagine something like Venus with huge mountains, like Mons Olympus type mountains. The upper atmosphere and those mountain peaks might be amenable to life.
Now imagine that same place had oceans of an alien variety. Maybe water trapped beneath the surface like lakes under Antarctica. And imagine those places could support life.
So you'd have two or more ecosystems that either never allowed life to move between them or they once were able to but no longer could.
You'd then have two environments where life could evolve completely independently. What a fascinating place that might be.
Earth definitely has places where evolution happened in a more-or-less isolated environment for a long time, though probably not from "zero".
For example Movile Cave: Life in the cave has been separated from the outside for the past 5.5 million years and it is based completely on chemosynthesis rather than photosynthesis.
Look up pictures from that cave at your own risk. Personally I think those critters are the stuff of nightmares.
I don't doubt there's an uncountable amount of ecosystems on Earth we haven't even found, much less understood. We (literally) have hardly scratched the surface of this planet.
 Recent progress in modeling imbalance in the atmosphere and ocean (2019) https://sites.ualberta.ca/~bsuther/papers/imbalance/reprint.... [pdf]
It's been suggested, in the context of preK science education, that students have a human right to make sense of their world "now". That's very not the focus of current content. But what might it look like?
Here, one might tell a 4 layer story. (Or maybe 6, with mantle and crust? - slightly-stirred,not,slightly,stirred,stirred,not?) Perhaps with near-surface deposition of sunlight energy stirring the middle layers. Perhaps integrated with a story of Earth's thermal-management BBQ roll, mixing too hot Sun and too cold deep space.
But integrated storytelling isn't what we're set up for. Especially when it requires direct-research expertise to explore for and craft viable stories, as here with "is the atmosphere an upside down ocean?".
I mention this to ask a meta question. I've struggled to find exploratory discussion, both of potential stories, and of the potential for such an approach. Any suggestions?
For a quick additional example, descriptive material properties like slimy, sticky, crunchy, firmness, and moldability, are kindergarten content. And they're quantitative rheological quasi-properties. But where might one explorationally discuss the possibility of students sorting K-familiar materials into Ashby-like diagrams?
If anyone has any thoughts, any at all, I'd appreciate hearing them. Thanks.
 tldr: https://hazen.carnegiescience.edu/research/mineral-evolution ; outreach talk: https://www.youtube.com/watch?v=_oiAVmgLPpY&t=468s ; paper: https://hazen.carnegiescience.edu/sites/hazen.gl.ciw.edu/fil...
We obviously live in a fluid the same as Aquaman. Except we can see, he'd just look at muddy water all day.
Humans have a very 2 dimensional mind, which makes us better than apes. We turn many variables into 2.
But we also lose out. There is no reason we can't have floating air cities except cost, which is less than a lot of things humans spend money on. For some reason everyone wants a floating city on Venus and not Earth.
Ocean farms are three dimensional, this has many advantages over land farming. Plus the ocean is most of the earth.
> On the Troposphere and the Thermocline
Summary by the author - "A seminar on the height of the tropopause, discussing the analogy with the oceanic thermocline"
"This talk draws on various papers, and is expanded in a more detail in the Walsh Cottage lectures above. A relevant technical paper is this one: https://empslocal.ex.ac.uk/people/staff/gv219/papers/ZG_Vall... "