Calculation formulas, Dewpoint temperature, Appendix b, calculation formulas – Vaisala AWS330 User Manual
Page 275: Appendix b
Appendix B ______________________________________________________ Calculation Formulas
VAISALA ______________________________________________________________________ 273
APPENDIX B
CALCULATION FORMULAS
This chapter contains information on the WMO-compliant calculation
formulas used in the measurements.
Dewpoint Temperature
The dewpoint component calculates the temperature, where dew is
beginning to form from moist air. This calculation is based on air
temperature and relative humidity.
Dewpoint temperature (t
d
) is calculated with the following WMO
(Annex 4.B) formulas:
⋅
−
⋅
⋅
=
)
(
112
.
6
´
ln
62
.
17
)
(
112
.
6
´
ln
12
.
243
p
f
e
p
f
e
t
d
and
)
,
(
´
)
,
(
´
100
t
p
e
t
p
e
U
w
d
w
⋅
=
which give:
(
) (
)
[
]
(
)
[
]
(
) (
)
[
]
(
)
[
]
100
/
12
.
243
/
62
.
17
exp
ln
62
.
17
100
/
12
.
243
/
62
.
17
exp
ln
12
.
243
t
t
U
t
t
U
t
d
+
⋅
⋅
−
+
⋅
⋅
⋅
=
Table 112
Inputs for Dewpoint Calculation
Input Variable
Air temperature (t)
TAAVG1M; see Table 4 on page 22
Relative humidity (U)
RHAVG1M; see Table 4 on page 22