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In this world, that rotates in the same direction and at the same rate as Earth, where the land platforms that cover around 10-20% of the world's surface is (magically) suspended at the 1 ATM level, 25km above a sea at which the atmospheric pressure is over 19 ATM, where the world's diameter is 22,282km, the gravity is 1g, and the scale height is equivalent to Earth's, about 8.5km. The solar energy received is sufficient to make the land at the 25km altitude have a temperature of about 15°C on average, with a sea-level temperature of around 130°C (below boiling point thanks to the atmospheric pressure).

The world's real surface is entirely covered in water, over which is a thick layer of low clouds, about 5km from the surface. There are also clouds above the ~25km platform altitude. The troposphere is 35-45 km high.

The platforms range in thickness from 1km to 10km, and are like entire continents floating in the air, with mountains on top and also beneath. They range from several hundred kilometres across to 10,000 km across.

Is it reasonable that the atmospheric circulation experienced by those dwelling upon those platforms would be the top of the cells, rather than the bottom, thus reversing the direction of the prevailing winds?

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  • $\begingroup$ I wonder how thick are your platforms. Do they accumulate enough heat over the day to act like dry land in the earthly wind circulation mechanism? And actually what's the effective troposphere height (from real surface) on that world of yours? It's possible that it's actually lower than your platforms, meaning they have a very low precipitation rate, rendering your winds problem less significant. $\endgroup$
    – Vesper
    Commented Oct 9, 2023 at 10:52
  • $\begingroup$ @Vesper, I've edited in the size of the platforms. The troposphere is going to be 35-45km high. $\endgroup$
    – Monty Wild ♦
    Commented Oct 9, 2023 at 11:12
  • $\begingroup$ Hmm with these sizes of suspended plates I'd say not plausible, not enough arguments tho. See, having a platform 10000km across at 25km height creates an area of permanent night below, which could (and will) cause a major weather disruption, probably down to those wind cells not even forming, or attached to plates somehow instead of latitudes. I say you'd better go with normal wind prevalence, as I'm totally baffled at how to account for such areas that are permanently dark but transparent to wind. $\endgroup$
    – Vesper
    Commented Oct 9, 2023 at 11:26
  • $\begingroup$ @Vesper Most plates are going to be ~5000km across or less, and cover ~15% of the surface of the world. The equator also doesn't have any significant amount of land over it. $\endgroup$
    – Monty Wild ♦
    Commented Oct 9, 2023 at 11:30
  • $\begingroup$ I say a 500-km wide plate is enough to disrupt surface heating for your planet, together with influencing surface-based winds, as your planet is type ocean it won't have mountains on the surface to block wind currents "down there", and convection would surely be affected somehow. Since you're effectively asking about global weather patterns, I deem it necessary to account not only for what's happening right over the plates, but also of what happens under them. And that thing looks quite complicated even without those rocks, not sure if Hadley cells are even applicable to ocean-type worlds. $\endgroup$
    – Vesper
    Commented Oct 9, 2023 at 11:55

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It depends on the level, in the atmosphere/sea of clouds, at which you see maximum/effectively total energy absorption, on Earth that's roughly sea-level for most intends and purposes. That level is where the base of your Hadley Cells will sit, if that held true on your proposed world, which I don't think it does, then the answer would be yes your floating continents would be high enough to experience "reversed" circulation.

That modelling assumes that circulation is driven purely by stellar radiation, if that were the case I think in fact the Hadley Cells on this world would have their bases somewhere in the upper atmosphere and sea level will be relatively dark and the sun a chilly smudge if visible at all. This would possibly put the floating continents at the level of the centre of the Hadley Cells leaving them alternately becalmed and buffeted by the up or down draft zones. However such a world may also have deeper atmospheric upwellings from heating in/under the ocean driving circulation cells from sea level which either override or interact with the radiation driven upper circulations.

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