Topic: Fisher Barometer for calibrating pressure

[Platokidd]

Santa was kind enough to bring me a Fisher Barometer. https://www.amazon.com/gp/product/B077CV7PJT/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Since December and serval tweaks it's been dialed in very well. Durning extreme highs or lows it may lag behind a point or two. Overall, this is one very nice barometer.

Now to my main reason for this posting in this section of the boards.

We're all (most all anyway) are aware of the shortcomings with Ecowitts and AW barometers. I personally recalibrate my consoles a few times a year with season change.
My plan is, to use this barometer for calibrating my ecowitt and AW consoles.

As to the Fisher Barometer and the effects of season change is the real question here.
Will this barometer need to be adjusted for other weather conditions / season changes throughout the year?



   

[Gyvate]

1. the "shortcomings" are not in the barometers - the local pressure is usually properly measured
what is usually not properly done is taking the temperature dependency of reduced air pressure (the local air pressure reduced to SLP or mean SLP) into account. Therefore the "fixed" offset, even calculated with the past 12 h average of the local temperature, remains a moving target. The console software should have the algorithm for minimising the temperature impact implemented and regularly calculate the reference SLP.

2. you could check the readings of your classical barometer against the local pressure readings  the consoles/a WH32B/indoor/WN32P provides. As you have probably eight consoles with inbuilt barometers and at least one WH32B, you could take their absolute (= local) pressure readings with abs offset = 0 and calculate the average: (p1 + p2 +p3 + ....+ p9) / 9 - and take the result as/for your local pressure.

You can also take the QFE value  from the METAR of your next airport, but unless it is level with you and really close by, it won't be your QFE.
QFE is local station pressure.

Your Fisher barometer just measures local pressure - it is not affected by the mathematical gimmicks of calculating the "proper" or "true" reduced SLP (of which anyhow always two exist, depending on your reference system).

I am pretty sure that our @gszlag will also contribute his two cents to the topic. ..

[gszlag]

As to the Fisher Barometer and the effects of season change is the real question here.
Will this barometer need to be adjusted for other weather conditions / season changes throughout the year? 

Nice gift!

Gyvate is correct. An aneroid barometer only measures local pressure.

If your console(s) are calibrated then all you have to do is set the needle to the ABS reading. Make sure all the barometers are at the same elevation.

A precision instrument like yours should be set to your elevation/altitude meaning you are setting to station pressure. Trying to compensate for temperature would not work very well.
 
Theoretically, you could calibrate to Altimeter and add a fixed elevation offset but mechanically, the set screw for precision altimeters is meant for making small adjustments.

You should set your Fischer to read station pressure which is equivalent to ABS in the FIne Offset ecosystem. Your barometer was probably calibrated at the factory - maybe at 200 meters? You will need to move the needle to calibrate to your own elevation.

If you feel that your consoles are not accurate enough, you will need to calculate the ABS(station pressure) for your aneroid barometer at its working elevation. To do this you can calculate your REL offset and subtract this from the Altimeter reading at a close-by airport.

EXAMPLE:

Altimeter reading (at the airport) minus REL offset = Station pressure (ABS)

Basically this is the same procedure to calibrate an Ecowitt display console except we are interested in ABS rather than REL.

For better accuracy redo this procedure  the next time when Altimeter = 1013.2. To check calibration,  add the REL offset to your current needle reading and compare it to the Altimeter reading at the airport. They should be close.

See the link (in my signature) to the barometer section in Gyvate's wiki for more info.
PS use the sensorsone web site to calculate the pressure difference (REL offset).

Edit: You can also use the Altimeter to Station pressure calculator to directly convert any Altimeter reading to station pressure without the math.
See https://www.weather.gov/epz/wxcalc_stationpressure

[Platokidd]

Thanks for taking the bait and replying.  I was hoping you two would jump in. Also know gszlag is a barometer addict and would not be able to resist.

This is a real eye opener. The Fisher barometer should be set to ABS and not REL by design, seriously. Yes, I set it to rel.
The Fisher came set to 0 meters. Per the paperwork in the box, that is what they preset for shipments to the US. The specs state 0m to 1000m so I'm good here. My elevation is 928 feet or 283 meters. Would think I did no harm calibrating the Fisher to rel as it would still be in spec.
 
I do have way too many sources (wh32 and consoles) for barometers. However, they are all set to use 1 wh32 T/H/P to simplify calibrating.
Thanks to the latest firmware update for HP25X0. That said, I pretty good at the calibrating the ecowitt's off-sets and believe I'm spot on.
I have 2 airports for reference fairly close by with one of them close to my elevation. Also use windy to check the isobars.

Now where to I go from here... Guessing, the right thing to do is set the Fisher barometer to ABS?... That with the off-set, I could still use it as another tool for calibrating my ecowitt consoles.

Again, thank you for jumping in here.
 

[gszlag]

Thanks for taking the bait and replying.  I was hoping you two would jump in. Also know gszlag is a barometer addict and would not be able to resist.

This is a real eye opener. The Fisher barometer should be set to ABS and not REL by design, seriously. Yes, I set it to rel.
The Fisher came set to 0 meters. Per the paperwork in the box, that is what they preset for shipments to the US. The specs state 0m to 1000m so I'm good here. My elevation is 928 feet or 283 meters. Would think I did no harm calibrating the Fisher to rel as it would still be in spec.
 
I do have way too many sources (wh32 and consoles) for barometers. However, they are all set to use 1 wh32 T/H/P to simplify calibrating.
Thanks to the latest firmware update for HP25X0. That said, I pretty good at the calibrating the ecowitt's off-sets and believe I'm spot on.
I have 2 airports for reference fairly close by with one of them close to my elevation. Also use windy to check the isobars.

Now where to I go from here... Guessing, the right thing to do is set the Fisher barometer to ABS?... That with the off-set, I could still use it as another tool for calibrating my ecitt consoles.

Again, thank you for jumping in here.

I would not worry about it. In this scenario there are no black and white answers. You can move the needle to match REL if you wish but for higher-end barometers, it is generally recommended to use station pressure. In your case, you will be using your Fischer as a reference instrument to calibrate other barometers. If so, it becomes clearer that station pressure(ABS) is preferred.

But ultimately, it is your call.

An analogue barometer is quite similar to the Ecowitt offset system as both are linear devices. For both systems you add a fixed number to station pressure to get a sea level equivalent pressure. When you received your barometer, how did its reading compare with your consoles ABS and REL readings?

[Platokidd]

Thanks for taking the bait and replying.  I was hoping you two would jump in. Also know gszlag is a barometer addict and would not be able to resist.

This is a real eye opener. The Fisher barometer should be set to ABS and not REL by design, seriously. Yes, I set it to rel.
The Fisher came set to 0 meters. Per the paperwork in the box, that is what they preset for shipments to the US. The specs state 0m to 1000m so I'm good here. My elevation is 928 feet or 283 meters. Would think I did no harm calibrating the Fisher to rel as it would still be in spec.
 
I do have way too many sources (wh32 and consoles) for barometers. However, they are all set to use 1 wh32 T/H/P to simplify calibrating.
Thanks to the latest firmware update for HP25X0. That said, I pretty good at the calibrating the ecowitt's off-sets and believe I'm spot on.
I have 2 airports for reference fairly close by with one of them close to my elevation. Also use windy to check the isobars.

Now where to I go from here... Guessing, the right thing to do is set the Fisher barometer to ABS?... That with the off-set, I could still use it as another tool for calibrating my ecitt consoles.

Again, thank you for jumping in here.

I would not worry about it. In this scenario there are no black and white answers. You can move the needle to match REL if you wish but for higher-end barometers, it is generally recommended to use station pressure. In your case, you will be using your Fischer as a reference instrument to calibrate other barometers. If so, it becomes clearer that station pressure(ABS) is preferred.

But ultimately, it is your call.

An analogue barometer is quite similar to the Ecowitt offset system as both are linear devices. For both systems you add a fixed number to station pressure to get a sea level equivalent pressure. When you received your barometer, how did its reading compare with your consoles ABS and REL readings?

 Set my Fisher barometer to the proper setting today, 993.4 hpa ABS (REL 1026.9) and rather steady. Will check again at 1013.2 and tweak if needed. Do want to add the Fisher to the toolbox per-say.

The barometer came set to 0 meters per the box stamp and note inside the box for US shipments. Thus, the reading was low when compared to my ecowitt's ABS reading (I think). At that time my focus was on setting the REL.

Needless to say, I am feeling rather

The Fisher is really nice looking on the wall!  Seems to be made very well and with precision quality!

[gszlag]

Good. Sounds like you've got things nailed down.The reason you double check at 1013.25 is that your REL offset is the most accurate at 1013.25 therefore you may need to tweak the needle a bit.

[Platokidd]

Good. Sounds like you've got things nailed down.The reason you double check at 1013.25 is that your REL offset is the most accurate at 1013.25 therefore you may need to tweak the needle a bit.

That's the plan.
After dialing it in more (if needed), hope I'm done turning the screw on the back.
Still getting used to looking at the needle on the other side of the dial. 
Hardly walk by without tapping slightly on the wall.
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[gszlag]

Beautiful. An addict aready! With a keen eye ,I expect you will soon be resolving down to 0.05 mb

After my next lottery win, I'll be looking at the 103 model.