Status - New record

[speedy]

ok, after a lot of reading this is how i understand this.

All weather stations should be displaying relative sea level pressure.

The adjustment required to obtain the relative sea level pressure for your station will depend on your altitude. Pressure decreases with altitude, so for every 8 metres in height pressure drops by 1 mbar. (sourced from the BBC met info)

So for example my closest offical weather station (birmingham airport) is currently reading 1019mb and the elevation at there station is 99 mtrs above sea level. My elevation above sea level (ground level elevation) is 110 mtrs so my station should now be reading 1.4mb less than the airports. (1019 - 1mb per every 8 mtrs = 1017.6 @ my stations current altitude)

(note mbar is the same as hPa)

Someone tell me that's right

Regards
Steve W.

[beteljuice]

.. My elevation above sea level (ground level elevation) is 110 mtrs so my station should now be reading 1.4mb less than the airports...

No !, you would expect your ABSOLUTE pressure to be different to the airports ABSOLUTE pressure.

The airports figures have already been tweaked to RELATIVE, on the assumption you are in a stable pressure area, your RELATIVE pressure should be the same as the airports RELATIVE.

Incidentally, airports actually report 'altitude' rather than baro (Don't even ask, it gets very complicated)

[speedy]

.. My elevation above sea level (ground level elevation) is 110 mtrs so my station should now be reading 1.4mb less than the airports...

No !, you would expect your ABSOLUTE pressure to be different to the airports ABSOLUTE pressure.

The airports figures have already been tweaked to RELATIVE, on the assumption you are in a stable pressure area, your RELATIVE pressure should be the same as the airports RELATIVE.

Incidentally, airports actually report 'altitude' rather than baro (Don't even ask, it gets very complicated)

Yeah your correct.... what i meant to say is that the relative adjustment figure for my height would be 1.4mb less than the airports.

and no i'm not going to ask about baro

[steve]

You were doing fine until you mentioned Birmingham and the elevation there

Basically, you don't need to worry about the elevation of the station you're using as a reference as they will be quoting sea-level pressure anyway. Just enter their sea-level pressure into your station at a time of stability and then your sea-level pressure will continue to read the same as their pressure from then on (ignoring other factors).

Steve

[Sadgit]

right... I am now 100% well and truly confused to hell!! I thought I had this all sorted in my head, hence my huge offset.. now I have no idea what I need to change

[steve]

right... I am now 100% well and truly confused to hell!! I thought I had this all sorted in my head, hence my huge offset.. now I have no idea what I need to change

You shouldn't use an offset in Cumulus for the purpose of setting your barometer to the correct sea-level pressure for your location. You should find a local station during a time of stable pressure and enter that station's reading (which will be corrected to sea-level) as your sea-level (relative) pressure in your station. Your station (and Cumulus, after restarting it) will then continue to show correct sea-level pressure.

Unless you actually want to understand the details of why this is necessary, you don't need to worry about your altitude or anyone else's altitude, or anything else.

Steve

[speedy]

Nicely put Steve.

Anyway whats wrong with Birmingham and altitude

I'm only short and everyone likes to get height dragged into it

Many thanks
Steve W

[tomcatuk]

Nicely put Steve.

I'm only short and everyone likes to get height dragged into it

Many thanks
Steve W

Vertically challenged I belive the PC brigade call it...

[Sadgit]

short ass is what people call me

Just installed the new build Steve and the new low barometer is now functioning as it should. Thanks for sorting that out (even though I don't need the adjustment after people showed me the light )

cheers
Mark

[Shawn]

This is my local station

http://www.metoffice.gov.uk/weather/uk/ ... ather.html

So the pressure reading they are showing is what i should have on my station as relative pressure?

As my station arrived is was set about 10 less so around 1018. As i write this my local station is 1029.

Shawn

[steve]

Yes, that's right. Your pressure looks spot-on.

Steve