Wind direction
Posted: Sun Mar 10, 2013 1:52 amSome people have mentioned that the wind direction on our weather station seemed off, so I climbed the tower on Saturday, taking down a defunct anemometer arm and adjusting the wind direction on the unit that feeds our web page.
I compared the indicated wind direction to hand held compass readings and the Bay Area Air Quality’s wind direction. The BAAQMD station does not average its wind direction, so while I did take multiple readings, because of the variations in direction at the time, I was not able to tell if they have adjusted for magnetic declination or not, which is +14 degrees at Fort Funston.
After taking a number of observations, watching the web page, and calling the wind talker, I decided to adjust the arm about 5 degrees to average true north with magnetic north. This way everyone should be happy, whether they use magnetic declination or not.
It is pretty hard to document a 7 degree difference in wind direction, but please feel free to stand at the clubhouse and compare your own readings with those on the web site. If there are strong feelings one way or the other, we can choose to use declination or not.
My personal opinion is that the wind sock is more relevant to our flying than a compass reading, and since the wind changes from hour to hour anyway, nit-picking the weather station might not be the best use of our energy. In any case, further adjustments are not hard to do!
I compared the indicated wind direction to hand held compass readings and the Bay Area Air Quality’s wind direction. The BAAQMD station does not average its wind direction, so while I did take multiple readings, because of the variations in direction at the time, I was not able to tell if they have adjusted for magnetic declination or not, which is +14 degrees at Fort Funston.
After taking a number of observations, watching the web page, and calling the wind talker, I decided to adjust the arm about 5 degrees to average true north with magnetic north. This way everyone should be happy, whether they use magnetic declination or not.
It is pretty hard to document a 7 degree difference in wind direction, but please feel free to stand at the clubhouse and compare your own readings with those on the web site. If there are strong feelings one way or the other, we can choose to use declination or not.
My personal opinion is that the wind sock is more relevant to our flying than a compass reading, and since the wind changes from hour to hour anyway, nit-picking the weather station might not be the best use of our energy. In any case, further adjustments are not hard to do!