Science Buddies: "Ask an Expert"

I was doing the make your own Psychrometer project. I don't know how to use the chart so I started to use the other method but I cant find an online calculator. Please tell me where this is.

Hi,

I found the reference to the online calculator in the Background section of the Scibuddies project: https://www.sciencebuddies.org/science- ... background

Here is the link to the calculator:
This webpage has an online calculator you can use to convert your psychrometer reading to relative humidity. In addition to your psychrometer reading, you will also need to know the barometric pressure:
Brice, T. and T. Hall, date unknown. "The Weather Calculator: Relative Humidity," National Weather Service Forecast Office, El Paso Area [accessed January 10, 2014] http://www.srh.noaa.gov/epz/?n=wxcalc_rh.

I tried using the calculator and I can't figure it out. There's a formula but that is even more complicated.

Here is another website I found that has a table for calculating relative humidity (RH) from the temp difference between the wet- and dry-bulb thermometers: https://www.google.com/url?sa=t&rct=j&q ... _A&cad=rja

To find out the % RH, all you have to do is look along the top line and find the column that corresponds to the difference between the dry-bulb and wet-bulb temp's and then look at the left side list of temp's until you find the dry-bulb temp and read that row across until you come to the temp difference column. That is the RH in %.

Hope this helps.

Sybee