Weather Banter - View Single Post - Weather station relative pressure setting

Gazza · February 7th 06, 04:28 PM posted to uk.sci.weather

wrote:
Gazza wrote:
I think I understand now. So if I enter the data from the BBC site into
my relative pressure setting the pressure display shown on the weather
station itself will adjust somehow using the entered value as a
reference and offset it somehow thus giving a different reading?

So how does the weather station know how much offset to add?

Thanks again in advance

Gary

That's why you have to enter the current sea level pressure - so that
it knows what the offset is!

Say the sea level pressure is currently 1025mb. The weather station
pressure sensor is reading 1015mb. The offset is 10mb, and once you
have entered it, this will allow the weather station to display correct
sea level pressure.

IIRC, atmospheric pressure falls by 1mb approx with every 9 metres
gained in altitude (at low levels). So the 10mb difference in my
example would be correct if you are about 90 metres above sea level.

Sorry for being real dim here but why I am getting confused is because
I am not sure if once I have entered the value from the BBC website
that the weather station should read the same thing as it doesn't - is
this correct? It does not seem right to me as I am entering a value
reported as the pressure and it reads something else??

Many many thanks for your patience.

Gary