"Doug Semler" wrote:

First off, it's psychRometric.

Do you understand relative humidity?

I thought so, but I foolishly trusted the spelling in the url.

Now, I am going to use the following readings:
104 degrees F for the temperature (the "official" high)
80 degrees F for the dew point.

According to the formula RH =~ 100((112 - .1T - Td)/(112 + .9T))^8,
where T = observed temperature and Td = dew point temperature, I get a
relative humidity of 88.32%.

We must be looking at different charts.