In this answer, I describe a low-density water world with a surface gravity of 1g and a surface atmospheric pressure of 20 ATM. The air temperature at the 1 ATM altitude (naively, assuming a temperature lapse rate of 0) of 25.25 km is 15°C.
However, if we assume a temperature lapse rate of 5°C/km, which is typical on Earth for wet air, which is highly probable on a water world, this would mean that (again, naively) the surface temperature would be about 141°, and at 20 ATM, the boiling point of water would be about 210°C. This would be the equivalent of having a surface temperature of about 67°C at 1 ATM, far closer to the boiling point of water than 15°C
So, I'm wondering if the temperature lapse rate might not reverse at some point in the lower atmosphere below the 1 ATM altitude, with a cloud layer increasing the planet's albedo and reducing the solar energy that reaches the surface.
Would this be a reasonable assumption? If so, at what altitude might such a lower cloud layer form?
Secondly, is it reasonable to assume that the weather on this planet would be more dramatic than on Earth, with higher winds and rainfall, even 25+ km above the surface?