The forum discussion centers on the application of the adiabatic equation to moist air ascending over a mountain range, specifically addressing the confusion regarding the heating effect of condensing vapor. Participants clarify that while the air parcel is heated by condensation, it remains adiabatic due to the internal energy changes balancing the expansion work done. The discussion also explores the calculations of equilibrium vapor pressure, mole fractions, and mass fractions of water vapor in moist air, emphasizing the use of the ideal gas law and Dalton's law for approximations. The final results indicate a mass fraction of approximately 6.9 grams of water vapor per kilogram of moist air at M1, with subsequent calculations leading to a consistent temperature prediction at M2.
PREREQUISITESThis discussion is beneficial for atmospheric scientists, meteorologists, and students of thermodynamics who are interested in the behavior of moist air in mountainous regions and the application of thermodynamic principles to real-world scenarios.
Very nice Jacob. Using the vapor pressure of ice at the final temperature, what do you now predict for the amount rained per kg?Jacob White said:So now after these corrections the final temperature I get is 270.89K which is about 0.6K higher than without considering ice. And that makes sense since we get some additional energy from freezing water.
It doesn't seem possible. What vapor pressure did you estimate at the final temperature?Jacob White said:Much more - about 3.737g.
That sounds right, but it implies 2.32 grams/kgJacob White said:0.5084 kPa