Vaisala AWS330 - Appendix Bcalculation Formulas; Dewpoint Temperature

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
´
ln62.17
)(112.6
´
ln12.243
pf
e
pf
e
t
d
and
),(´
),(´
100
tpe
tpe
U
w
dw

which give:










    
100/12.243/62.17expln62.17
100/12.243/62.17expln12.243
ttU
ttU
t
d






Table 110 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