(41) Atmospheric Humidity

[SlideRule]

The "Programs for Calculating Atmospheric Humidity" can be retrieved from Historical Instrument Conservator's Comuter Users' web page as Applications Note 83-1 Programs for Calculating Atmospheric Humidity. The PDF file also includes a Relative Humidity listing for the Casio FX-602P as well as barcode for the HP-41c.

Enjoy!

[SlideRule]

(04-12-2018 08:09 AM)Mike (Stgt) Wrote:  … Did you ever use that program? In which units did you enter the values? …

Source document for the HP-41 program:
Calculating Atmospheric Humidity
Author(s): Cary Karp
Source: Studies in Conservation, Vol. 28, No. 1 (Feb., 1983), pp. 24-28
Published by: Maney Publishing on behalf of the International Institute for Conservation of Historic and Artistic Works
Stable URL: http://www.jstor.org/stable/1506103
Accessed: 21-10-2015 11:13 UTC
REFERENCES
Linked references are available on JSTOR for this article:
http://www.jstor.org/stable/1506103?seq=...b_contents
with the following excerpt:
"CALCULATING ATMOSPHERIC HUMIDITY
Cary Karp
Abstract-Derivations are given for the functional relationships between psychrometric and barometric observations, and the commonly encountered atmospheric humidity parameters. The use of a programmable pocket calculator is recommended for the practical application of the material".

Table 4.1 from this article follows:

Code:

4.1 List of symbols used
t    = dry bulb temperature in °C
tw   = wet bulb temperature in °C
p    = barometric pressure in kPa (l kPa = 10 mbar)
em   = saturation partial pressure of water vapor at dry bulb temperature in kPa
emw  = saturation partial pressure of water vapor at wet bulb temperature in kPa
rp   = relative humidity as a decimal fraction (RH/ 100)
A    = the psychrometer constant: 0·00066 for water on wet bulb; 0·00058 for ice on wet bulb
a, b = coefficients used in finding saturation partial pressures of water vapor:
       a = 17·25, b = 236-9 for 0°C and above;
       a = 22·27, b = 270·8 for below 0°C
x    = the mixing ratio (in kg/kg)
h    = specific enthalpy in kJ/kg

As to my utilization, I'm sure the answer is yes, at some time in the past, since the material is in my personal archives. Member(s) who can not secure the source documents via the given references are welcome to PM their inquiry & I will reply accordingly.

My primary motive for providing the link(s) mirrors the conservation site - historical preservation. Many members might otherwise never access this material. Pegging off your posting seemed like a good idea, perhaps not?

BEST!
SlideRule

[WrongWay]

Thank you! For another source of the same information: https://wahiduddin.net/calc/density_altitude.htm
I wrote a C++ calculator using the above website.