Campbell Scientific UT20 and UT30 Tower-based Weather Stations - Manual (Page 63)

UT20 and UT30 Tower-based Weather Stations
8.5.17 Enclosure Humidity Sensor
Mount the CS210 inside the environmental enclosure or onto a datalogger
using the mounting block and the wire tie included with the sensor (FIGURE
8-32).
The black outer jacket of the cable is Santoprene ® rubber. This
compound was chosen for its resistance to temperature extremes,
moisture, and UV degradation. However, this jacket will support
combustion in air. It is rated as slow burning when tested
according to U.L. 94 H.B. and will pass FMVSS302. Local fire
codes may preclude its use inside buildings.
FIGURE 8-32. CS210 installed on a CR1000
8.5.18 Wind Direction Sensor Orientation
8.5.18.1 Determining True North and Sensor Orientation
Orientation of the wind direction sensor is done after the datalogger has been
programmed, and the location of True North has been determined. True North is
usually found by reading a magnetic compass and applying the correction for
magnetic declination*; where magnetic declination is the number of degrees
between True North and Magnetic North. Magnetic declination for a specific site
can be obtained from a USFA map, local airport, or through the National
Geophysical Data Web site at: www.ngdc.noaa.gov/geomag. A general map
showing magnetic declination for the contiguous United States is shown in
FIGURE 8-33.
Declination angles east of True North are considered negative, and are subtracted
from 360 degrees to get True North as shown FIGURE 8-34. Declination angles
west of True North are considered positive, and are added to 0 degrees to get True
North as shown in FIGURE 8-35. For example, the declination for Logan, Utah is
16° East. True North is 360° – 16°, or 344° as read on a compass.
Orientation is most easily done with two people, one to aim and adjust the
sensor, while the other observes the wind direction displayed by the datalogger.
NOTE
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