Appendix A _________________________________________________________________ Glossary
VAISALA _______________________________________________________________________ 193
The sea level pressure as QNH, but the value is corrected by the
actual air temperature (or in some cases by virtual temperature, that
is, temperature 12 hours ago). QFF is used in synoptical
observations. QFF is calculated using the following formula:
QFF QFE e
HR
7996 b HR 29.33 TA
=⋅
+⋅ + ⋅
where
b = 0.0086 °C/m
HR = Station altitude [m], set by the altitude command
QFF
TA = Actual air temperature [°C] measured by MAWS
QMH102
The humidity and temperature probe for MAWS. Temperature is
measured with a Pt-100 and humidity with HUMICAP
®
180 sensor.
QML102
The logger of MAWS.
The atmospheric pressure at sea level in the standard atmosphere.
The station altitude is indicated by station altitude setting in MAWS
(difference of mean sea level and station altitude). QNH is used for
aviation purposes. QNH is calculated using the following formula:
QNH QFE e
0.03416 HR (1 d)
288.2 c HR
=⋅
⋅⋅−
+⋅
where
HR = Station altitude [m], set by the altitude command.
d=
0.19025 ln
QFE
1013.2315
⋅
QNH (altimeter
setting)
c = 0.00325 °C/m
Rain gauge
Measures precipitation based on depth, that is, the depth to which a
flat surface would be covered if no water were lost by run-off or
evaporation.
RS-232
Standard serial transmission protocol. A standard interface between a
computer input/output port and a peripheral device.
RS-485
Standard serial transmission protocol. This protocol permits multi-
drop networks (up to 32 nodes) using a single twisted pair cable.
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