New Zealand Local Weather Forum

Management => Questions and Answers => Topic started by: JennyLeez on March 11, 2012, 01:19:28 AM

Title: Why does Weather Station Software only report up to 99% for Humidity.
Post by: JennyLeez on March 11, 2012, 01:19:28 AM
In my travels recording the high and low humidity it has become apparent that very few stations are reporting 100%. They report only up to 99%.
Looking around Cumulus I found this software gives you the ability to report 100% and a box to tick.
2 questions. Why does weather station software only report up to 99% and secondly can Weather Display be configured to report 100% as opposed to 99%.

Thanks
Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: Tony on March 11, 2012, 08:39:26 AM
The software is only recording what the hardware feeds it

La Crosse stations only report to 97%  >:( 

I had noticed that feature in Cumulus and thought it was a good one.

Tony
Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: TokWW on March 11, 2012, 09:04:43 AM
My latest La Crosse hygro reports to 98% or 99% not sure which, old one was limited to 95%.  But in WD you can force it to modify the output which is in integer values, to either add an offset, and add an "add-on" gradient to lift the top range up a bit back from about 75%. 

The instruments are hard to calibrate to give the 100%, I think TT's Davis one, over accentuated the 100% for too long a period, or was that someone else's?  David's perhaps?  I don't know.  It is very hard to design a device that reads it accurately.
Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: David on March 11, 2012, 09:17:53 AM
My Davis station usually maxes out around 98%. Occasionally I get a spike to 99% or 100% for a few seconds then it drops back again - so I think that is some sort of minor problem with the sensor.

I use the set 98% humidity as 100% in my weather software
Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: JennyLeez on March 11, 2012, 10:23:52 AM
So in WD can you alter somewhere to make 98 or 99% report 100%

Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: David on March 11, 2012, 10:27:30 AM

You can't set 99% as 100% it seems, but you can for 96, 97, or 98:
Control panel -> Offsets and initial rain -> Humidity offsets
Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: TokWW on March 11, 2012, 10:29:34 AM
Yes.Control Panel and [Offsets and initial rain], but you may need the Slope adjustment feature to get 99% to 100% but it will not give 101% etc.  It crops it at 100.
Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: JennyLeez on March 11, 2012, 10:44:34 AM
I have mine set in Cumulus as well David 100%.

Anyone reading this should make these adjustments in either cumulus or WD if they wish their station to report 100%.
Thanks you guys for input.

Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: beteljuice on March 11, 2012, 11:08:00 AM
Two problems:

If you artificially adjust the top end, you lose the bottom end (approx. 15% - which is why most people shouldn't be trying to compute 'Burning Index') - It also means all your dew points are changed.

So be careful what you wish for  ;)
Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: GrantK on March 11, 2012, 12:57:59 PM
My Davis VP2 frequently reports 99% and occasionally 100% humidity.  My previous Honeywell station seldom went above 90%.
Title: Re: Why does Weather Station Software only report up to 99% for Humidity.
Post by: JennyLeez on March 11, 2012, 01:06:58 PM
Hi :)

What I have started to pick up is software also is controlling this figure as with cumulus allowing the 100% to be reported or not.

Cheers