Vaisala AWS330 - Page 280

User's Guide ______________________________________________________________________
276 _________________________________________________________________ M211296EN-A
0.10)))1.0((000662.0)1.0(( 







hitwetAAwetwsder
PTTTTPP
T
wet
0:
)T-(TP0.000583 - )(TP = P wetAAwetwihit 

10.0) P - 0.1))+(T-(TT0.000583 - 0.1)+(TP ( = P hitwetAAwetwider 


where
T
wet
=
Wet bulb temperature [C]
T
d
=
Dewpoint temperature [C]
T
A
=
Ambient air temperature [C]
P
A
= Ambient air pressure [hPa]
P
ws
(t) = Aqueous vapor pressure of water at temperature t [hPa]
P
wi
(t) = Aqueous vapor pressure of ice at temperature t [hPa]
P
ws
(t) is calculated with the formula:
01.0)log(43210
1_
exp)(
32







 vbvbvbvbb
v
b
tP
ws
where
b_1 = -5800.2206
b0 = 1.3914993
b1 = -0.048640239
b2 = 0.000041764768
b3 = -0.000000014452093
b4 = 6.5459673
v = t - c0 - c1  t - c2  t
2
- c3  t
3
where
t = Temperature [K]
c0 = 0.4931358
c1 = -0.0046094296
c2 = 0.000013746454
c3 = -0.000000012743214