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.
