Originally Posted by scsims
So absolute is for if you have a portable weather station device??
Yes, the response you got was a round about way of saying that most weather stations and pressure reports are adjusted for sea level based upon the altitude.......it's a way to report consistent readings across a statewide or regional area. Attitude and pressure are directly related and the higher the altitude the lower the pressure....take a state line NM with elevations ranging from 3,000 to over 13,000 feet.....if pressures were not adjusted to sea level a pressure map would make it look there is a low pressure area over every mountain range.
Check out this sticky thread for more details.
Altitude vs. Barometric pressure
In short if you updating from the web absolute=off.....with a kestrel calibrated for zero elevation absolute= on.
Hope this helps...........