User's Guide _______________________________________________________________________
192 __________________________________________________________________ M210243en-A
Lull
The minimum of wind speed during a certain time interval (as
defined in the wind calculation module of MAWS).
Modem
A device that allows a terminal or computer at one location to
communicate with a terminal or computer at a distant location via
wire or telephone lines.
Precipitation
Term that refers to all forms of water particles that fall upon the
earth. This includes rain, snow, and hail. It is the universal practice
to distinguish between rain, snow, and total precipitation. Snow is
sometimes measured as such and sometimes it is melted and
measured as water.
Pslevel
The pressure sensor level in meters from the station altitude.
Pyranometer
An instrument that measures solar energy received from the entire
hemisphere (180 degrees field of view). The output is expressed in
Watts per square meter (W/m
2
).
The actual atmospheric pressure at the level of station altitude or at
the height of the runway threshold. The difference of the pressure
sensor level and the station altitude (or runway threshold) is
indicated by the pressure sensor (pslevel) setting in MAWS. QFE is
normally used for aviation purposes. QFE is calculated using the
following formula:
QFE PA e
HS
7996 b HS 29.33 TA
=⋅
+⋅ + ⋅
where
PA = Station pressure measured by MAWS [hPa]
HS = The height of the pressure sensor from the station level or
from the runway threshold level [m], set by the pslevel
command
b = 0.0086 °C/m
QFE
TA = Actual air temperature [°C] measured by MAWS
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