For example, the declination for Longmont, CO (10 June 2006) is 9.67°, thus True North is 360° –
9.67°, or 350.33° as read on a compass. Likewise, the declination for McHenry, IL (10 June 2006) is
–2.68°, and True North is 0° – (–2.68°), or 2.68° as read on a compass.
FIGURE A-2. A declination angle east of True North (positive) is subtracted from 360 (0)
degrees to find True North
FIGURE A-3. A declination angle west of True North (negative) is subtracted from 0 (360)
degrees to find True North
Appendix A. Determining True North and wind sensor orientation
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