So laying out a few things here: a planet has an atmosphere about 3.5 times denser than Earth with a marginally cooler average temperature (about 12 Celsius). It has a basic Nitrogen/Oxygen Mix, but with twice as much water vapour (0.5%).

Would it cause clouds to rise higher before precipitation occurs or would the higher percentage of water vapour cancel it out? How high could the clouds get?

The world has large mountain ranges that cast a lot of rain shadows but I was wondering if the clouds might simply pass over them if they get high enough.

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    $\begingroup$ The clouds are not made of water vapor. Water vapor is a transparent invisible gas, just like air. The clouds are made of little droplets of liquid water, or little crystals of solid ice. And here on Earth we get clouds from zero elevation above ground (which is usually called "fog") to about 80 km above sea level... $\endgroup$
    – AlexP
    May 22, 2023 at 13:12

1 Answer 1


A denser atmosphere will not by itself force clouds higher. Cloud formation is a function of pressure (equivalent to density for atmospheres of constant composition) and temperature, and partial vapor pressure.

Clouds form when air reaches saturation, which occurs as temperature drops in an air mass with constant vapor pressure. So, where clouds form on your world compared to our will depend on how you managed that increase in water vapor percentage in the atmosphere. You can do that either by increasing the total area of exposed surface water on the planet, or raising surface temperatures. In order to double the mean percentage of water vapor in the air at a constant pressure, you would need higher temperatures--maintaining that percentage while increasing the total atmospheric pressure 3.5 times mean you need even higher temperatures. Increased surface temperatures by themselves would have pushed cloud levels higher... but with that increased humidity level, you will see clouds pulled back towards the ground again.

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    $\begingroup$ Small addition, the point of saturation is largely independent from the air pressure. But the air forces the water vapor to be at a certain temperature. $\endgroup$ May 22, 2023 at 14:41
  • $\begingroup$ cheers for this explanation, looks like i was conflating some of my variables, I'll wrap my head around it eventually lol $\endgroup$
    – Rexotec
    May 23, 2023 at 0:34

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