Saturation vapor pressure, Θ+ θ, Tc t – Vaisala HMT130 User Manual
Page 90
User's Guide _______________________________________________________________________
88 ___________________________________________________________________ M211280EN-B
Saturation Vapor Pressure
The saturation vapor pressure (P
ws
) is the equilibrium water vapor
pressure in a closed chamber containing liquid water. It is a function only
of temperature, and it indicates the maximum amount of water that can
exist in the vapor state.
The water vapor saturation pressure P
ws
is calculated by using two
equations (6 and 7):
∑
=
−
=
Θ
3
o
i
i
i
T
C
T
[
]
hPa
(6)
where
T = Temperature in K
Ci = Coefficients
C0 = 0.49313580
C1 = -0.46094296 * 10-2
C2 = 0.13746454 * 10-4
C3 = -0.12743214 * 10-7
∑
−
=
Θ
+
Θ
=
3
1
4
ln
ln
i
i
i
ws
b
b
P
(7)
where
bi = Coefficients
b-1 = -0.58002206 * 104
b0 = 0.13914993 * 101
b1 = -0.48640239 * 10-1
b2 = 0.41764768 * 10-4
b3 = -0.14452093 * 10-7
b4 = 6.5459673