Appendix B. Humidity Equations And Conversion Chart; Introduction; Vapor Pressure - GE Optica Operator's Manual

Appendix B. Humidity Equations and Conversion Chart

B.1 Introduction
The following symbols appear in the equations below:
e
= Vapor Pressure, millibars
e
= Vapor Pressure with respect to ice, millibars
i
e = Vapor Pressure with respect to water, millibars
w
e
= Saturation vapor pressure, ice, millibars
is
e
= Saturation vapor pressure, water, millibars
ws
P = Total Pressure, millibars
T = Temperature, °C
T
= Ambient temperature, °C
a
T
= Dew point temperature, °C
d
T
= Frost point temperature, °C
f
B.2 Vapor Pressure
Saturation vapor pressure with respect to water is a function of temperature only and is given by the following:
Saturation vapor pressure with respect to ice requires a minor adjustment of the constants as given by the following:
In addition to yielding saturation vapor pressure as a function of ambient temperature, the above equations also yield
ambient vapor pressure as a function of dew/frost point.
The total pressure of a gas mixture is equal to the sum of the partial pressure each gas would exert, were it to occupy
the same total volume, according to Dalton's law.
Optica™ Operator's Manual
6.1121EXP 17.502T
E =
----------------------- -
WS
240.97 T
6.1115EXP 22.452T
E =
----------------------- -
IS
272.55 T
Appendix B. Humidity Equations and Conversion Chart
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