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Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sat 24 Oct 2009 10:29 am
by 6719jason
Good Morning,

I was wondering if anyone else had encountered the following happening, During an After Rainfall:

Humidity falling rapidily to sometime's 10%
Dew Point falling rapidily to below -0.0

Yet, stations nearby have the complete reverse and their figures make sense, I.E Humidity near 95% and Sensible Dew Point Temperature.

This only appears to happen during Rainfall and for around 24hrs following the End of Rainfall.

I realise Rainfall has a cooling effect and is rather refreshing, but I am curious as to the effect of the rainfall and this station.

Trend Graphs and Data are available on the website.

Many Thanks

Jason

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sat 24 Oct 2009 3:53 pm
by akasonny
So Jason,

When its raining, how high does your humidity/dew point rise before falling?

Obviously, those readings after a rainfall don't make sense. I find myself wondering about whether your rain collector is blocked somehow.
6719jason wrote:Good Morning,

I was wondering if anyone else had encountered the following happening, During an After Rainfall:

Humidity falling rapidily to sometime's 10%
Dew Point falling rapidily to below -0.0

Yet, stations nearby have the complete reverse and their figures make sense, I.E Humidity near 95% and Sensible Dew Point Temperature.

This only appears to happen during Rainfall and for around 24hrs following the End of Rainfall.

I realise Rainfall has a cooling effect and is rather refreshing, but I am curious as to the effect of the rainfall and this station.

Trend Graphs and Data are available on the website.

Many Thanks

Jason

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sat 24 Oct 2009 4:07 pm
by 6719jason
akasonny wrote:So Jason,

When its raining, how high does your humidity/dew point rise before falling?

Obviously, those readings after a rainfall don't make sense. I find myself wondering about whether your rain collector is blocked somehow.
Well, What I meant to put in that posting was, it falls to 10% and below and the same effect with the Dew Point Temperature.

I have checked the Rain collector and it is not blocked.

Photograph of setup below:
SL372332.JPG
Jason

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sat 24 Oct 2009 5:03 pm
by akasonny
Thats quite a puzzle, Jason.

I don't know if this could be related but I noticed when the batteries in my transmitter were failing that I was getting inermittent readings in various areas at the console. Might be a thought.

The only other thing that comes to mind is the possibility of some sort of interference on or near the operating frequency.

I admit I'm as confused as you are.

[/quote]

Well, What I meant to put in that posting was, it falls to 10% and below and the same effect with the Dew Point Temperature.

I have checked the Rain collector and it is not blocked.

Photograph of setup below:
SL372332.JPG
Jason[/quote]

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sat 24 Oct 2009 9:46 pm
by 6719jason
NEWS FLASH!

I was wondering if someone could take a look at my Trend Graphs Asap.
Only,I noticed that it all went haywire, after 3:30am this morning, when I had 154mm/hr Rainfall Rate and around 12.3mm Rainfall in one go!
I was wondering if this might be related to this issue?

Jason

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sat 24 Oct 2009 9:54 pm
by akasonny
Certainly a clue, eh?
6719jason wrote:NEWS FLASH!

I was wondering if someone could take a look at my Trend Graphs Asap.
Only,I noticed that it all went haywire, after 3:30am this morning, when I had 154mm/hr Rainfall Rate and around 12.3mm Rainfall in one go!
I was wondering if this might be related to this issue?

Jason

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sat 24 Oct 2009 10:03 pm
by 6719jason
Indeed it is, But I want to know why it happens and How to prevent it happening again :D

A worthwhile solution is required for all owners of such stations, mine cant be the only one, cant it?

Jason

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sun 25 Oct 2009 12:36 am
by Super-T
Jason
If you fire up easyweather, does the same show in the data?

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sun 25 Oct 2009 12:40 am
by 6719jason
Yup. Same data.

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sun 25 Oct 2009 12:47 am
by Super-T
The only time I have had such erroneous data is when I have had to remove the batteries and restart for nay reason. Maybe battery contact corrosion?
I have smeared petroleum jelly over the battery lid and other possible openings for water and that seems to help.
The other day I had a bad solder joint on my usb connection in the console and that caused strange readings with disconnection and reconnection at random or when I leaned over to answer the phone and moved the usb cable. :-)

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sun 25 Oct 2009 12:48 am
by Super-T
anyway Jason.....it's too late to be awake and on the internet for you :-)

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Sun 25 Oct 2009 12:56 am
by 6719jason
Super-T wrote:anyway Jason.....it's too late to be awake and on the internet for you :-)
Tell me about it, though I gain an extra hr in 5mins :D

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Mon 26 Oct 2009 6:26 pm
by 6719jason
Good Evening Steve,

I wondered if you might have some ideas on this rather unusual problem?

I am also wondering if, It would be possible to have a Ignore Setting in Cumulus V1, for use when the
Dew Point temperature (currently calculated by Cumulus, I think) and Humidity Levels dont seem to
go with the Current Weather Conditions, if you see what I mean.

As you will have read from my first post and those following, the problem only occurs in Rainfall.

Any comments, thoughts or solutions would be great appreciated :)

Nice to have you back with us on the forum Steve,

Jason

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Mon 26 Oct 2009 7:24 pm
by steve
I'm not sure what Cumulus could do about it; it sounds like a hardware fault with your humidity sensor, rather than one of the 'design' issues with Fine Offset stations that I have to try to work around.

Re: Rainfall Effect on Humidity and Dew Point Temperatures......

Posted: Mon 26 Oct 2009 7:48 pm
by Repairman77
Jason; just a thought; is rain getting into the transmitter box; either though the vents or in through the plugs and sockets.
This would certainly account for gross inaccuracies from the sensors.
I've now sealed all around the plugs with some soft putty type decorator's filler. Easy to get off if need be but keeps out any water.
I'm not sure if your transmitter box and cover is the same as mine on the WH1080 but if so it does seem to be woefully inadequate in stopping water ingress in heavy weather conditions.
Mike.