Gases are either present in a mixture or not. Unlike a solid dissolving (or not) in a liquid, there are are no immiscible gases. When water vapor is liberated, either the air will go elsewhere or the local pressure will rise. Air is displaced by the presence of water vapor, in accordance with Dalton's Law of Partial Pressures.
There is no affinity between water vapor and air.
ArthurOgawa 00:42, 23 September 2007 (UTC) I agree that the notion of air "holding" moisture is flawed. Or, a reference to an explanation should be added. In what way is the condensation of water out of, say, air not a manifestation of the saturation of a solution? I propose removing this language as a gratuitous editorialization (the claim is neither supported nor explained). The notion that air "holds" moisture, or that moisture dissolves in dry air and saturates the solution at some proportion, is an erroneous (although widespread) concept.įrankly, I do not see Rkinch's point. Under the heading Psychrometric Chart, Relative Humidity, Rkinch added ArthurOgawa 00:42, 23 September 2007 (UTC) Inappropriate editorialization Any diagram using enthalpy as one of its axes can be called a Mollier diagram, by decree of some physicists at a conference in 1923. Old Mollier must have really been working hard in those days! Tex 15:12, 11 April 2006 (UTC) See Richard Mollier. In fact I have never heard the enthalpy-composition diagram, as discussed here, called a Mollier diagram, but apparently it can be. Probably the next most common is the pressure-enthalpy, or ph diagram. The most common is the enthalpy-entropy, or hs diagram. 57.66.65.38 10:25, 11 April 2006 (UTC) This is a little confusing because in fact several different thermodynamic diagrams are known as "Mollier diagrams". This external link shows the relation between the Mollier diagram and the Psychrometric chart. Tex 23:39, 20 February 2006 (UTC) Mollier diagram
#Ashrae psychrometric chart big pdf
Thanks njh 20:54, 20 February 2006 (UTC) The relevant chapter can be downloaded from the ASHRAE website as a PDF file, for a fee which is greater than nominal but not outrageous. I can probably deduce it from the Clausius-Clapeyron relation though. Note that it's published in English and metric editions. Most libraries should have a copy in the reference section. Look in Chapter 6, Psychrometrics, under Numerical Calculations of Moist Air Properties, to find what you are looking for. The standard source is the ASHRAE Handbook: Fundamentals. This calculation is trickier than it looks.
ArthurOgawa 00:08, 23 September 2007 (UTC) Dew Point Formulas So the curve involved has to be measured. The relationship is not a matter of definition, but relates to the physics of water and air. See Arden_Buck_Equation and references therein. Looking at the graph the wet bulb temps appear to be a constant gradient intersecting the saturation curve but how is this derived? njh 10:16, 11 January 2006 (UTC) I've looked around the net and there seems to be a lack of formulae.