If you want better calibration precision than the 0.01 inHg you are getting now then switch to hPa (which are the same as millibar). When you calibrate using hPa you can be more precise. But you don't have to permanently switch to seeing hPa, rather this is just an exercise during calibration of the console. Then when it is dialed in you can then switch the console to showing you inHg if that is what you prefer and the calibrations done while under hPa are still realized.
Use this site to convert units while calibrating. https://www.convertunits.com/from/hpa/to/inhg Although you probably won't need to convert pressure units if you use a METAR data website like NOAA Aviation Center because that should show both units. https://aviationweather.gov/metar/ Do know that for locations with elevation higher than 3,000 feet that barometric calibration is a bit more of a challenge. On Tuesday, January 12, 2021 at 3:12:20 PM UTC-5 [email protected] wrote: > * On 2021 12 Jan 13:40 -0600, galfert wrote: > > Stop saying that the airport is at the same elevation or at different > > elevation from you. That is extraneous and irrelevant information. > > I am merely attempting to be factual as I'll admit to being still a bit > confused as to what unit the METAR from my airport shows, whether > barometer or altimeter. No matter, I shall not concern myself with that > any longer. > > > Use this sight to find out your elevation: > > https://www.freemaptools.com/elevation-finder.htm > > I think Google Earth is better for this purpose as the satellite view > lets me pinpoint my house exactly. This site has not such view that > I've seen and there is a hill side from the west around to the east and > even being 100 yards off can mean a difference of 20 to 40 feet, maybe > more, of elevation. > > > If you don't have the latest firmware then you may not have Loop2 data. > Not > > having Loop2 data will inhibit greater Altimeter calculation by WeeWX > > because station pressure will be missing and it will have to work > backwards > > and that is less accurate. Better to send the software station pressure > > which is done by having Loop2 data. > > According to the Davis site the latest firmward for the Vantage Pro2 is > 3.15 and wee_device reports my console is at 3.15. I have not specified > which LOOP data WeeWX is to use as I assume it is coded to use the best > available format. > > > Do not attempt to constantly calibrate your station with the airport. It > is > > perfectly normal for there to be times when your pressure and the > airport > > are experiencing different pressures, meaning you'd both be right by > each > > showing what is occurring at each location. If you want to know why then > > study isobars. I wrote this little piece which might introduce the > subject, > > but I think you should read more about it to fully grasp the concepts. > > https://www.wxforum.net/index.php?topic=36579.0 > > I set the Correction Constant to 0 last night with wee_device and right > now the airport shows 30.08 and my station is at 30.09. However, there > is a falling tendency right now. I plan to leave things as they are and > let it run for some time with no correction. > > > There are also other reasons than isobars when the pressure could be > > different between your location and the airport and that has to do with > > differences in equipment and how pressure is calculated internally by > the > > hardware. Different times of the year when the average temperature is at > > extremes will also cause for more discrepancies. Therefore the best time > to > > calibrate your barometer is when: > > > > > > - when the METAR indicates the pressure is very near 1013.25 hPa > > - at the top of the hour when METAR data is most current > > - when the pressure is steady > > - when it is midday > > - when it is good weather > > - when the temperature *outside* is close to 15°C (least critical) > > Thanks. > > - Nate > > -- > > "The optimist proclaims that we live in the best of all > possible worlds. The pessimist fears this is true." > > Web: https://www.n0nb.us > Projects: https://github.com/N0NB > GPG fingerprint: 82D6 4F6B 0E67 CD41 F689 BBA6 FB2C 5130 D55A 8819 > > -- 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/5a95d729-97ea-4a43-aa72-1bf096411355n%40googlegroups.com.
