I believe you are incorrect, unless I’m misunderstanding your point. Air can indeed be ‘supersaturated’ in which vapor pressure is higher than saturation. RH greater than 100% is definitely possible.

Supersaturation is not prolonged, but for cloud formation, supersaturation must be greater than 0.

Yep

See you saying that air at the same temperature that is more humid is lighter?

I also approached the question this way. The change in relative humidity within the space would depend on whether the dewpoint inside is higher or lower than the dewpoint outside. From a humidity control standpoint, a rainy day at 60F will result in a very muggy interior because the there is enough infiltration to meet the sensible load but the rh could be 70% or more. It all depends on what counts as “cold” for a rainy day.

Since no one was willing to take a stab at this question, I will give the answer. Humid air is less dense than dry air. The difference isn’t a lot, but most people I know think that humid air is “heavier”.

My other comment is a nit pick. The question was if I had experienced conditions greater than 100F/90%. My answer was yes, it was in a sauna in Finland, not an ambient condition, but I have experienced it.

Hey Jay,
100% of the information is from DPCALC.org and there is an older version with more columns and all of those figures also come from the same place. Their formulas are really useful but not when you are presented with the whole spectrum versus the relavant sections only, and also “MY CHART” had to have some rounding out of necessity and as simple as it is people refuse to read the accompanying write-up. The main benefit of both of “MY CHARTS” is the limited temperature range, and the explanations at the bottom. Lots of people who store baseball cards, books, boxes, library systems ACTUALLY USE THIS CHART. You might never find the standard charts in use by anyone other than the author of an article about how tricky it is.

Adam

That is an interesting chart in the link you shared. Do you know the source of this data?

Interesting argument for possibly not needing dehumidification in a well sealed crawl space. I wouldn’t want to get too close to the point where there is a possibility of a mold issue.

RoyC

Agreed that the two lines for Wet Bulb and Enthalpy are almost parallel and thus wouldn’t work for defining a point. If nothing else, a little inaccuracy in one or both would throw the point way off.

As I recall if you have any other two properties of a moist air condition you can use them to find the exact point on the psych. chart.

This would include specific humidity, enthalpy, DB Temp, WB Temp, RH, DP Temp.

Actually for the above besides enthalpy and WB, you also can’t use specific humidity and DP temp together. Specific humidity and DP Temp lies are actually parallel.

This is the number one google result on Earth if you search “ Mold Chart”: https://energyhandyman.com/knowledge-library/mold-chart-for-temperature-and-humidity-monitors/

The purpose, is for use with standard temp and RH sensors, and to help people not to open their windows maybe. The phrase “Mold Chart for Temperature and Relative Humidity Sensors” or something similar is searched on Google millions of times a month by people who have already found the chart provided in this article.

Stay unconfused my friends.