[wxqc] Sensor drift

[spamfree]

Hi,

It being a WM-II does make a difference. 

Two thoughts come to mind. First, Davis kind of implies that the barometer is not temperature compensated when they state in the manual "The barometer may be less accurate at extreme temperatures [i.e., less than 50°F (10°C) or greater than 90°F (32°C)].  Also, given the way the barometer is set, I'm assuming they use a fixed calibration offset to adjust for elevation. However, the algorithm for calculating a true altimeter value does not produce a static delta between sensor pressure and altimeter over all pressures. For example, at an elevation of 460 ft., if the sensor pressure is 960.00 mb, the altimeter would be 975.94 mb (a delta of 15.94), and if the sensor pressure is 1020.00 mb, the altimeter would be 1036.75 mb (a delta of 16.75). So, it's possible you could see see a drift of 1 mb as your pressure systems pass over your area.

Steve
  
======= At 2006-05-22, 10:40:43 you wrote: =======

>Hi Steve,
>
>    I guess I should have specified the station.  I've got the WM-II and 
>not the Vantage or pro model.  I know there is a bit of difference 
>between the two.
>
>Sam
>
>_______________________________________________
>wxqc mailing list
>wxqc at lists.gladstonefamily.net
>http://pond1.gladstonefamily.net:8080/mailman/listinfo/wxqc
>
>The contents of this message are the responsibility of the author.