1. If you use hardware record generation, then windSpeed is whatever is reported by your hardware. If you use software generation, then windSpeed is the average over the archive interval. 2. If you use hardware record generation, then windDir is whatever is reported by your hardware. If you use software generation, then windDir is calculated from the vector average. 3. Zero wind speed has an undefined wind direction. But, see option ignore_zero_wind <http://weewx.com/docs/usersguide.htm#StdWXCalculate>. 4. No idea. 5. If you use hardware record generation and your hardware reports wind gusts, then that is used. If you use software generation, then windGust is the highest value seen in the archive interval. 6. If you use hardware record generation and your hardware reports wind gust direction, then that is used. If you use software generation, then windGustDir is the direction of the wind at the time the highest value was seen in the interval.
All of the above is from the perspective of weewx. In your situation, where you have to work with the raw data, I'm not sure this is much help. In particular, watching the wind vane on my anemometer, it swings wildly. Some sort of averaging, even if over a few milliseconds, is probably essential. Hope this helps. -tk On Sun, Oct 9, 2016 at 1:15 PM, Max Frister <[email protected]> wrote: > Now that i've got my homebrew station installed and working, I'd like to > clear up some of my confusion about how wind speeds and directions are > calculated. > > Can anyone point me to some authoritative information. In particular I > would like to answer: > > 1. Is there a standard period for averaging wind speeds? I found one > document that said 3 seconds sampled every 1/4 second and averaged. > > 2. Are averages supposed to be scalar or vector (i.e., taking wind > direction into account)? > > 3. Does a 0 wind speed have a direction? > > 4. My cup anemometer puts out a sine wave with a frequency proportional to > wind speed. The frequency ranges from about 0.7Hz to 60Hz. Such low > frequencies are often measured using reciprocal counting (i.e., measure the > period). Are there preferred techniques or algorithms for doing that? A > simple technique just counts the number of zero-crossing (tick's) per > measurement period, but that is only approximately correct. > > 5. What is a gust? One very unhelpful definition I saw was the highest > "instantaneous" measurement. Is that right, or does it need to last for a > certain period of time? > > 6. What is the gust direction? If a gust really is an instantaneous > sample, then given the momentum of the gauge the direction corresponding to > that gust probably is lagging. > > > Thank you for any help. > > -- > You received this message because you are subscribed to the Google Groups > "weewx-user" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
