Water Vapor Computations

Over Water Over Ice
Saturated H2O Partial Pressure (mbar)
Saturated H2O Mixing Ratio (ppm)
Water Mixing Ratio (ppm)
Dew Point Suppression               K/C        F
Dew Point Temperature K   C   F

Temperature K   C   F

Pressure (mBar)

Hold This Constant %RH Over Water
%RH Over Ice
Mixing Ratio (ppm)
Dew Point Suppression
Dew Point



The water in the atmosphere is typically expressed in different ways, depending on the source. One of the purposes of this application is to easily convert between some of these. Unfortunately, Precipitable water refers to the total atmospheric column and, therefore, can not be converted into a local value.

The values calculated above are presented to much higher precision than can be justified by the known precision of the instruments used to make the measurements. While laboratory instruments are fairly accurate, sensors used to collect real world (field) RH values are less than 1% accurate. Therefore, for practical purposes, values within +/-2% RH should be considered identical.

Explaining Dewpoint and Relative Humidity to the Public presents an interesting discussion. Basically,


Author: Robert Clemenzi
URL: http:// mc-computing.com / Science_Facts / Water_Vapor / Water_Vapor.html