I have a super-earth world. The surface of the world is shallower due to extra gravity, so shorter mountain ranges and less ocean depths. The world orbits a binary star system at a distance of the furthest region of the habitable zone, both of the stars having masses of 0.93x that of our suns. The world is highly volcanic, approximately 15 to 16 times more volcanic than our planet.

Surface gravity: 1.35x of Earths.

Atmosphere density: 10x of Earths (a result of it being highly volcanic in comparison to earth.)

Atmospheric composition: Nitrogen 78%, 15% Oxygen, 5% Carbon dioxide, 2% Trace gases.

Temperature: rather hot, the tropical regions being 90 to 110 degrees Fahrenheit. (based on what I've tested on Universe Sandbox 2)

Land coverage: 75% water, and 25% land (but less water being present on this world as the oceans oceans are shallower mostly due to a lot of island formations)

Radius: 7750 kilometers

Day/Night length/full rotation: 28 hours.

Axial tilt: 53 degrees.

Orbital period: 1.15 years

Eccentricity: 0.025

In an atmosphere of approximately 15 bars, can you get evaporation identical to Earths at sea level with temperatures below 35 degrees Celsius?

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    $\begingroup$ Venus has an atmospheric pressure of 90 bar, and clouds form just fine. It's all about relative humidity and temperature differential at altitude. $\endgroup$ – RonJohn Aug 3 '18 at 16:32
  • $\begingroup$ Could you please elaborate on what would be the problem? Off the top of my head I cannot think of any reason why water wouldn't evaporate. (And sublimate; never forget that water sublimates rather easily.) BTW, you are probably aware that the atmosphere described would not be suitable for humans. $\endgroup$ – AlexP Aug 3 '18 at 17:47
  • $\begingroup$ the tropical regions being 90 to 110 degrees Fahrenheit That's 32 C to 43 C. That's probably on the low side for a 15 bar surface pressure, which would imply a very strong greenhouse effect, I think. $\endgroup$ – StephenG Aug 3 '18 at 20:46
  • $\begingroup$ Atmosphere thickness: 10x of Earths For a 1.35 surface gravity this sounds unrealistic (regardless of volcanic activity being 16x Earth average). $\endgroup$ – StephenG Aug 3 '18 at 20:48
  • $\begingroup$ @StephenG That is completely realistic. Venus has less surface gravity than Earth and a higher pressure. $\endgroup$ – Jarred Allen Aug 3 '18 at 22:21

If you would like to boil water at an atmospheric pressure of 15 bar, the difference would be significant. The boiling point temperature would be increased to about 198 °C compared to about 100 °C at a pressure of 1 bar. The enthalpy of vaporization would be increased from about 1946 kJ/kg to about 2257 kJ/kg. Thus, you would have to supply more energy to evaporate water by boiling at the same rate.

However, if you just want to let water slowly evaporate at a given temperature of 35 °C, the difference would be small. At a temperature of 35 °C, the equilibrium vapour pressure of water is about 0.056 bar. This equilibrium is almost unaffected by the pressure of the other gases in the given range, i.e. the equilibrium vapour pressure mainly depends on temperature. The effect of the absolute pressure difference between 1 bar and 15 bar on the equilibrium vapour pressure is probably less then 5 %, which can be neglected compared to the effects of even small temperature differences.

  • $\begingroup$ Oh.. so would I be able to get conditions that of a tropical rainforest in such a world? Would the humidity still be relatively high for precipitation to occur? $\endgroup$ – Neuryte Aug 4 '18 at 19:32
  • $\begingroup$ @Neuryte Yup. For practical purposes your 15 bar means nothing to the weather. $\endgroup$ – Loren Pechtel Aug 5 '18 at 4:29
  • $\begingroup$ @LorenPechtel, that's excellent! Though I'm assuming the clouds would look different? By means of being possibly more flat and dense..? $\endgroup$ – Neuryte Aug 5 '18 at 5:48
  • $\begingroup$ @Neuryte I don't know what's going to happen to your clouds. $\endgroup$ – Loren Pechtel Aug 5 '18 at 22:52

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