I have recently aquired and set up WH1081 weather station (purchased from Maplin as N96FY) which seems to work very satisfactorily although I have one problem -
It is possible to adjust the relative air pressure to match that of my local met station (at RAF Benson) and over time they remain well attuned, however if I then switch to absolute pressure the reading is clearly incorrect. There appears to be no way of adjusting the absolute pressure. Any ideas, please?

Ello and Welcome to the Forum.

Firstly, The Absolute Pressure CAN NOT BE ADJUSTED! So, we will move onto the Relative Pressure.

Right, to correct the relative pressure to an adjusted figure I would suggest you do the following:

Visit the following website, Wind Map - Britain Observations , I suggest you wait until there is an area of high pressure as that way, the variation in readings caused by real time, 30 minute and 60 minute reporting from the airports will average itself out, Find the nearest Location to you......

Close Down 'Cumulus' if running. Open up 'EasyWeather', then open up the 'Setup' Window. Then find down the bottom of that Dialogue Window, The Realtive and Absolute Boxes (Absolute will be greyed out) and enter the figure given by your nearest location from the XC Weather or Met Station into the Realtive Box and then Click save.

You have now corrected the Relative Pressure.

Any more questions, please dont hesitate to ask

Jason

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Jason, many thanks for the reply. I have already found out how to adjust the relative pressure and had done so successfuly. I have been monitoring this against my existing barometer and it appears to be in line. My problem is that on the weather station it is possible to change the reading from relative to absolute. I had assumed that if one was set the other reading would bear some relativity to it? If the absolute reading cannot be changed then (I would assume that) it should be registering the correct absolute pressure - or thereabouts. As my elevation is about 330ft if I set the relative pressure to (say) 993 hpa and if I then change the reading across to absolute I would expect the reading to be higher, however in practice it isn't, it actualy reads 990 hpa! My local Met station station (Benson) gives the absolute pressure as 1000 hpa.

David

David,

Thats good, I am pleased that went sucessfully. I believe the 'Console' Display can be set to 'Display' the 'Absolute' Pressure instead of the 'Relative' Pressure. This can also been done in 'EasyWeather' Settings.
You may also find this tool Above Sea Level Barometer Reading Correction Calculator
Useful.

Quote from user guide:
ABSOLUTE AIR PRESSURE
Absolute air pressure is the actual air pressure on the barometer without regard to altitude.
RELATIVE AIR PRESSURE
Relative air pressure is the same as the barometric pressure. The calculation of relative air pressure is a
combination of the absolute air pressure and the altitude.

To be honest with you, I would use the above tools, alongside your readings from the Met Office Site, to get your relative pressure as close as possible to your readings, taking into consider your altitude and try not to worry about the Absolute.
I have found my Absolute is normally way higher than the Relative. As expected.

Hope this helps

Jason

P.S Can really recommend 'Cumulus' for displaying your Data on the Web and in the Home

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If your Absolute is 990, why have you gone below sea-level and set Relative to 993 ?

Are you sure Benson is giving Absolute pressure ? - It means nothing without knowing its altitude.

Regardless of what your station considers Absolute, wait for a large stable pressure area, and set your Relative to that.

Should be approx. 1003 hPa at the moment.

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David,

At the time of posting, Benson is showing 1003mb. I find the attached link quite a good site for cross reference.

Wind Map - Britain Observations

Alan.

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Addendum to my previous post.

I have two other stations within a 6 mile radius of me. All three are Davis and we are all at the same altitude, give or take a meter, (Lincolnshire Fens). It is very rare for all three to have exactly the same pressure readings. Granted it is only probably 1mb, but there is a difference.

You will see from my signature that my altitude is almost sea level


Alan.

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That is just the point, I would have expected the absolute pressure to be higher but if I change my weather station to show absolute pressure it shows a lower reading than the relative reading (which I know is correct).

But you also said Benson was reporting 1000 hPa, so why set to 993 ?

.. Something isn't adding up ..

But as long as you have your Relative set 1002.5 => 1003.5 for now, you can tweak later.

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