Ambient Weather WS-12 User Manual page 28

speed calibration factor from 0.75 to 1.25, where:
Calibrated Wind Speed = Calibration factor x Measured Wind Speed
Note: The wind gust is also affected by the wind speed calibration factor.
Discussion: Wind speed and wind gust are adversely affected by installation constraints. The
rule of thumb is to install the weather station four times the distance of the height of the tallest
obstruction (for example, a 6 m house would require an installation 24 m away).
In many instances, due to trees and other obstructions, this is not possible. The wind speed
calibration allows you to correct for these obstructions.
In addition to installation challenges, wind speed bearings (any moving part) wears over time. To
correct for wear, the correction value can be increased until the wind cups must be replaced.
Without a calibrated source, wind speed is a difficult parameter to measure. We recommend using a
calibrated wind meter and constant, high speed fan.
2. Rainfall Calibration (1 Hour, 24 Hour, Daily, Monthly, Total). Press the
the Rain Calibration value will begin flashing (the default is 1.0). Press the [+] or [-] button to adjust
the rain calibration factor from 0.75 to 1.25, where:
Calibrated Rain = Calibration factor x Measured Rain
Discussion: The rain collector is calibrated at the factory based on the funnel diameter. The
bucket tips every 0.01" of rain (referred to as resolution). The accumulated rainfall can be compared
to a sight glass rain gauge with an aperture of at least 4".
Note: that debris and insects can collect inside the tipping mechanism (they make a good
spiders nest). Carefully remove the funnel and inspect the tipping mechanism for debris prior
to calibration.
3. Absolute Pressure and Relative Pressure Calibration. Press the SET key again to enter the
absolute pressure and relative pressure calibration mode. Press the [+] or [-] key to increase or
decrease the pressure reading (in increments of 0.01inHg)
Note: The display console displays two different pressures: absolute (measured) and relative
(corrected to sea-level).
To compare pressure conditions from one location to another, meteorologists correct pressure to
sea-level conditions. Because the air pressure decreases as you rise in altitude, the sea-level
corrected pressure (the pressure your location would be at if located at sea-level) is generally
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key again and
SET
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