Feeling pressured

I'm confused — horribly confused.

I finally decided to get around to sorting out the relative pressure setting on the WS3600. I dug out an OS map of my area and checked my height above sea level (about 10 meters) and then, using this article to guide me, worked out what the relative pressure setting should be (around -1.25hPa based on that document if I'm reading it correctly).

So far so good.

According to the manual that comes with the station it says that I should subtract that value off 1013.0hPa in the "Relative Pressure" setting in the unit's configuration menu. So, I dived into that configuration item only to find that the value in there was something totally different. After a little head scratching I realised that the value I was seeing in there was the current relative pressure reading — not some sort of base value that I needed to fiddle with.

I made an attempt to adjust the value anyway (as you'll see starting from around here) and I think it's changed things in the right direction but it hasn't actually got it right yet.

As of the time of writing my station is showing an absolute pressure of 1019.9hPa and a relative pressure of 1011.2hPa. I've been wondering if it will suffice to simply set the relative pressure to 1019.9 - 1.25 (in other words: current absolute minus offset) — while that probably still wouldn't be spot on I get the impression it would be closer to correct. I've been looking at the values for stations near me (as of the time of writing: RAF Cranwell showing 1023hPa, Grantham showing 1022.3hPa and Branston showing 1022hPa) but I'm not sure if I should be reading those values as relative or absolute values. All are close to the absolute value I've got at the current time (and, of course, I'm close to sea level).

Like I said: I'm horribly confused now.

I think I've got some more reading and learning to be doing...

File Under: WS3600, Relative Pressure, Absolute Pressure.

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