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At suggestions, I've started this for those who wish to discuss whether you calibrate your PWS anemometer vane to true north or magnetic, such as myself, pros and cons.
C.D.M.V.T.?I used the "true" heading from this FFA picture for TIA:
CWOP wants true north in siting guide. http://www.wxforum.net/index.php?topic=21081.0;nowap
While we all strive for perfection, in reality how much does it really matter? If you are off by 5° what are the consequences?
Quoting the lyrics "...whichever way the wind blows..."11.1ºE in 2005 -- at 0.1ºW per year -- means in 2015 "true" north has drifted to 10.1ºE magnetic.
I would say even getting within 40 degrees with eyeballs is a win. Much harder than you would think. I tweak afterward with software.
Quote from: ValentineWeather on November 02, 2015, 09:53:48 PMI would say even getting within 40 degrees with eyeballs is a win. Much harder than you would think. I tweak afterward with software.40!!! Remind me to NEVER let you operate on me!
Never substitute a Proctologist-MD for a Neurologist-MD.
Quote from: Old Tele man on November 02, 2015, 10:53:46 PMNever substitute a Proctologist-MD for a Neurologist-MD. But I did stay at a Holiday Inn Express.
http://flighttraining.aopa.org/magazine/1998/August/199808_METAR_Winds_True_or_Magnetic.htmlthis list airports that do not give wind in magnetic heading. Also marine weather reports use true headings instead of magnetic.John
Everything is EXACT...except for the EXCEPTIONS (ha,ha)!
I think the real question here is how do we set a standard for aiming the anemometer. I'm grappling with that same question as I consider siting my flagpole for this. I have a short pole for the system now and aimed it at Polaris as best I could. For a deeper discussion about "North" consider reading the WiKi about True, Celestial, and Magnetic Norths. https://en.wikipedia.org/wiki/True_northMagnetic North is changed periodically, so maybe Celestial is the more stable reference. "North" only refers to some arbitrary place until it is defined and fixed with a bench mark.
Just asking what level of accuracy do you want? How far will you go to calibrate your instrument? GPS? Is it accurate? HAhaha! I aimed mine at Polaris when I had a clear night. Celestial. JMHO.
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