Vaisala AWS330 User Manual
Page 278
User's Guide ______________________________________________________________________
276 _________________________________________________________________ M211296EN-B
0
.
10
)
))
1
.
0
(
(
000662
.
0
)
1
.
0
(
(
⋅
−
+
−
⋅
⋅
−
+
=
hit
wet
A
A
wet
ws
der
P
T
T
T
T
P
P
T
wet
≤
0:
)
T
-
(T
P
0.000583
-
)
(T
P
=
P
wet
A
A
wet
wi
hit
⋅
⋅
10.0
)
P
-
0.1))
+
(T
-
(T
T
0.000583
-
0.1)
+
(T
P
(
=
P
hit
wet
A
A
wet
wi
der
⋅
⋅
⋅
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(
4
3
2
1
0
1
_
exp
)
(
3
2
⋅
⋅
+
⋅
+
⋅
+
⋅
+
+
=
v
b
v
b
v
b
v
b
b
v
b
t
P
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