FAQ: Difference between revisions

Cumulus displays pressure corrected to sea level. The console calls this ‘relative pressure’; it displays the letters "rel" when this is being displayed. The Fine Offset stations only supplystore absolute/station pressure toreadings in their weather memory locations updated with each transmission and read by Cumulus,. soWithin Cumulus, the software applies the adjustment to sea level before any further processing. It does ''not'' use the altitude setting in the cumulus station configuration screen.

Normally when Cumulus starts, it reads in [http://www.jim-easterbrook.me.uk/weather/mm/ the pressurefixed ‘offset’block] in (the differenceconsole betweena pair of absolute/station pressure and relative/sea level pressure) fromreadings and uses the difference between these as the ‘offset’ in millibar for the station; itCumulus uses this offset subsequently to calculate the sea level pressure (each time when reading the absolute pressure sentin the weather memory locations fromof the station), but it is possible to define the offset in [[Cumulus.ini#Introduced_for_problems_with_Fine_Offset_family.2C_but_may_be_more_widely_applicable:| cumulus.ini]] instead.

Sometimes the offset that cumulus reads from the fixed block is clearly garbage, so Cumulus uses zero instead as a best effort. In this situation, Cumulus will display the same value as the 'absolute' pressure on the console (no "rel" is displayed on the console when it is displaying absolute pressure). Often, if you restart Cumulus, it will then be able to read the correct value. If the problem happens often, you can circumvent it by editing cumulus.ini (while Cumulus is stopped), and in the [Station] section add an entry:

where x.y is your pressure offset. '''Cumulus will then use this instead of reading itthe fixed block offset from the station'''.