Vaisala HMT130 - Manual (Page 88)

User's Guide _______________________________________________________________________
86 ___________________________________________________________________ M211280EN-B
P
w
is the water vapor pressure (see the equation below). The parameters
A, m, and T
n
depend on temperature according to the following table:
T A m Tn
… 0 °C 6.119866 7.926104 250.4138
0 ... 50 °C 6.1078 7.5000 237.30
50 ... 100 °C 5.9987 7.3313 229.10
100 ... 150 °C 5.8493 7.2756 225.00
150 ... °C 6.2301 7.3033 230.00
Dew/frostpoint Temperature
Dew/frostpoint temperature is calculated using:
1
log
0
0
−






= → <
= → ≥
A
P
m
T
T T
T T T
w
n
df d
d df d
[ ]
C  (2)
P
w
is the water vapor pressure (see the equation below). The parameters
A, m, and T
n
depend on temperature according to the following table:
Td A m Tn
… 0 °C 6.1134 9.7911 273.47