Hello,
I was on WU Today and noticed a rather high pressure reading from a nearby Station and this is clearly the result of uncalibration - See http://www.wunderground.com/weatherstat ... =ISUFFOLK2
Just a heads up here
It is worth adding....that at the time of this post...there was a 40HPA difference between this station and those in the surrounding area...Including Met Office Stations!
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Latest Cumulus MX V3 release 3.28.6 (build 3283) - 21 March 2024
Cumulus MX V4 beta test release 4.0.0 (build 4021) - 04 May 2024
Legacy Cumulus 1 release 1.9.4 (build 1099) - 28 November 2014
(a patch is available for 1.9.4 build 1099 that extends the date range of drop-down menus to 2030)
Download the Software (Cumulus MX / Cumulus 1 and other related items) from the Wiki
The Result of Uncalibrated Barometers....
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The Result of Uncalibrated Barometers....
Last edited by 6719jason on Fri 05 Mar 2010 7:31 pm, edited 1 time in total.
- Repairman77
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Re: The Result of Uncalibrated Barometers....
I have two military stations near me at Mildenhall and Lakenheath and the barometers as well as the hygrometers (far worse) can be very different, although they are only about 2 miles apart.
The barometers are in sync today at 993.00 but the Hygrometers are showing 80.9% and 93.2%!
I'd guess the second one to be somewhere near as mine is showing 84%.
While we are on the subject of accuracy has anyone ever tested the accuracy of the WH1080/90 series of anemometers?
I've often wondered how accurate they are.
Mike.
The barometers are in sync today at 993.00 but the Hygrometers are showing 80.9% and 93.2%!
I'd guess the second one to be somewhere near as mine is showing 84%.
While we are on the subject of accuracy has anyone ever tested the accuracy of the WH1080/90 series of anemometers?
I've often wondered how accurate they are.
Mike.
Retired Radio and Electronics Engineer residing in Cambridgeshire, UK.
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Re: The Result of Uncalibrated Barometers....
Looking at the history for the month doesn't look far off, and then 14th & 15th silly readings, back to normal ish, then back to what I assume is full scale on the 26th
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Alan
Alan
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Re: The Result of Uncalibrated Barometers....
Jason, what make you think that your station barometer is better calibrated than the one displaying its results on Weather Underground?6719jason wrote:I was on WU Today and noticed a rather high pressure reading from a nearby Station and this is clearly the result of uncalibration...
When you installed you station, did you get some high-precision instruments to calibrate your weather station (and I do not mean using the data from nearby weather stations) - and do you regularly recalibrate your station using those same high-precision instruments? I think not...
Our weather stations are as accurate/precise (and calibrated) as our knowledge of our weather stations goes ... and of the instruments we initially use to calibrate and we regularly use to recalibrate our weather stations ... no more, no less...
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Re: The Result of Uncalibrated Barometers....
I calibrated mine against the Met Office station at Dunkeswell air field, just a few miles away. The best I could do. I check again every so often when the pressure is fairly even over the area.
Gina
Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.
Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.
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Re: The Result of Uncalibrated Barometers....
I have no real answer to that, like Gina, I calibrated mine and do reguarly using nearby Airports and Met Office Stations. Mine also keeps in line with a Davis station nearby - A Vantage Pro 2 I think from memorygemini06720 wrote:Jason, what make you think that your station barometer is better calibrated than the one displaying its results on Weather Underground?6719jason wrote:I was on WU Today and noticed a rather high pressure reading from a nearby Station and this is clearly the result of uncalibration...
Not at all. When I first set up the station, I knew little about what I was doing. Still dont really. In short, No. If I could afford those high precision instruments, I wouldnt have a Fine Offset station.gemini06720 wrote: When you installed you station, did you get some high-precision instruments to calibrate your weather station (and I do not mean using the data from nearby weather stations) - and do you regularly recalibrate your station using those same high-precision instruments? I think not...
Yeah.gemini06720 wrote: Our weather stations are as accurate/precise (and calibrated) as our knowledge of our weather stations goes ... and of the instruments we initially use to calibrate and we regularly use to recalibrate our weather stations ... no more, no less...
Will be replying to your email as soon as I can.
WWS
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Re: The Result of Uncalibrated Barometers....
I expect the pressure sensors are pretty accurate. Mine certainly keeps in line with my oldfashioned wall barometer, and also with the one at the airport nearby.
The most likely inaccuracy of any barometer system will be in the offset that is introduced to bring it into line with the convention of giving Relative Pressure - the pressure at sea level. If there is a high pressure system over an area with few isobars on the weather map, you can align yours to a trusted, nearby station. But if you know the precise altitude of your station above sea level, you can use this Java calculator to work out exactly how much offset to put in. Once that is done, you shouldn't fiddle with it again.
http://www.csgnetwork.com/barcorrecthca ... m=990.2990
If you want to know your exact station altitude, you can use Google Earth to find it.
The most likely inaccuracy of any barometer system will be in the offset that is introduced to bring it into line with the convention of giving Relative Pressure - the pressure at sea level. If there is a high pressure system over an area with few isobars on the weather map, you can align yours to a trusted, nearby station. But if you know the precise altitude of your station above sea level, you can use this Java calculator to work out exactly how much offset to put in. Once that is done, you shouldn't fiddle with it again.
http://www.csgnetwork.com/barcorrecthca ... m=990.2990
If you want to know your exact station altitude, you can use Google Earth to find it.
My weather data page on WU:
http://www.wunderground.com/weatherstat ... =INEWCAST6
http://www.wunderground.com/weatherstat ... =INEWCAST6