Author Topic: Rain gauge might not be right  (Read 9323 times)

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Offline phil2010

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Rain gauge might not be right
« on: May 12, 2010, 10:59:25 AM »
It might be correct, but I haven't had a rain gauge before and its rained for the first time since Ive had it. It was raining quite heavy for about 10 - 15mins and its reported 1mm, doesn't this sound a bit on the low side? Apparently every tip of the gauge is 1mm or 0.04 inches

Offline 4wd

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Re: Rain gauge might not be right
« Reply #1 on: May 12, 2010, 11:31:42 AM »
It can't be that far out so long as it gets the signal OK and the bucket taps too and fro OK
It needs to be level of course.
Give it longer and ideally compare to nearby stations on wunderground or similar.
It is surprisingly difficult to estimate how much there's been 'visually'.
You might eventually work out it's only counting every other tip or something - you could test that easily.

Offline George Richardson

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Re: Rain gauge might not be right
« Reply #2 on: May 12, 2010, 11:36:13 AM »
Hey Phil,
Actually, the bucket could have been just ready to make a second tip so your gauge could be correct and you actually had 0.075 inches of rain, which is quite a lot. I promise you, if you get a Davis unit which tips every .01 inch, you could get quite wet standing in the rain beside the unit waiting for the first tip!
FWIW
George

Offline stevebrtx

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Re: Rain gauge might not be right
« Reply #3 on: May 12, 2010, 03:36:07 PM »
I used to think the same, seemed like it took a lot of rain to tip once to get .04" - but then again as noted, you could have been one drop short of a second tip and you'd never know. There are notes here, pinned I think, on a modification to add a funnel to increase the capacity to .01" per tip. I did mine last year and now it seems much more real. But then again, we're on day 83 of "not a single drop of rain" and may not get any for at least another 3-4 weeks - but, we're ready when it finally comes.

We basically don't get any rain for 8 months, can you imagine how "tired" the console gets of hearing the rain gauge check in and say "nope, no rain"?

Offline phil2010

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Re: Rain gauge might not be right
« Reply #4 on: May 12, 2010, 03:48:55 PM »
I used to think the same, seemed like it took a lot of rain to tip once to get .04" - but then again as noted, you could have been one drop short of a second tip and you'd never know. There are notes here, pinned I think, on a modification to add a funnel to increase the capacity to .01" per tip. I did mine last year and now it seems much more real. But then again, we're on day 83 of "not a single drop of rain" and may not get any for at least another 3-4 weeks - but, we're ready when it finally comes.

We basically don't get any rain for 8 months, can you imagine how "tired" the console gets of hearing the rain gauge check in and say "nope, no rain"?

83 days without rain, where do you live :shock:, Im from the UK, and its always bloody raining here.

Offline sam2004gp

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Re: Rain gauge might not be right
« Reply #5 on: May 12, 2010, 04:26:36 PM »
Phil, here is the OS rain Gauge Modification that Steve spoke about.  http://www.wxforum.net/index.php?topic=2738.0

If you have any questions just post them here.
SAM --->>> http://www.mountcrawfordweather.org
OS WMR-968 with a Dedicated PWS Weather Computer running VWS v13.01 p09


Offline stevebrtx

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Re: Rain gauge might not be right
« Reply #6 on: May 12, 2010, 05:01:09 PM »
83 days without rain, where do you live :shock:, Im from the UK, and its always bloody raining here.
Yes, I know it's hard to imagine living where you do, but I'm in the mountains of central MX, just S of Guadalajara and we have rain from about the middle of June through Sept. It starts one day as if by magic and ends like shutting off a faucet. Yet, we're called "the land of eternal Spring" because we have flowers and flowering trees etc. year round, we don't have heat or AC in our houses (just fans and usually a small propane heater), I wear shorts most of the year - it's a tough life, but someone has to do it.

(Now, all the above it true, but the other side of the coin is that I have dirt streets on both ends of the place I rent + a dark green car, so I think of it as 8 months of dust and 4 months of mud)

PS: I've never been to the UK, but I'd bet "mi casa" probably doesn't look anything like what you're used to:
http://www.flickr.com/photos/47655945@N06/sets/72157623423091761/show/

PSS: I didn't mean to imply anything, I only rent the place, just thought you might enjoy seeing something different.
« Last Edit: May 12, 2010, 05:40:12 PM by stevebrtx »

Offline phil2010

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Re: Rain gauge might not be right
« Reply #7 on: May 14, 2010, 03:48:33 AM »
Its rained again last night, Im not sure how long for tho but its only reporting another 1.1mm or 0.04inches. Ive noticed theres beads of rain on the funnel, I thought all the beads were ment to run in the bucket? Is there anything I can polish on the funnel to make the beads of rain run in?

Offline DanS

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Re: Rain gauge might not be right
« Reply #8 on: May 14, 2010, 03:51:30 AM »
Use the stuff for car windshields to repel rain, like rain-x for example. Car wax works pretty good too.

You could place something like a coffee can next to it to compare. Rough but will give you an idea what's happening anyway. Example, you measure 1/4" (6.35mm) in the can and only get 1 tip would be a clue.
« Last Edit: May 14, 2010, 04:12:47 AM by DanS »

Offline phil2010

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Re: Rain gauge might not be right
« Reply #9 on: May 14, 2010, 04:17:28 AM »
Use the stuff for car windshields to repel rain, like rain-x for example. Car wax works pretty good too.

You could place something like a coffee can next to it to compare. Rough but will give you an idea what's happening anyway. Example, you read 1/4" in the can and only get 1 tip would be a clue.

Thanks I'll buy some rain x and see if that does the job, this wont damage the surface of the funnel at all?? Also I'll put a glass jar beside it to see if its the same reading. good idea DanS,

Offline DanS

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Re: Rain gauge might not be right
« Reply #10 on: May 14, 2010, 04:21:42 AM »
No the rain-x shouldn't be a problem. Lots of folks on here do it.
Good luck and fill us in after the next rain.

Offline phil2010

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Re: Rain gauge might not be right
« Reply #11 on: May 14, 2010, 06:41:15 AM »
Well it deff not working right, cos its been raining on and off all morning and it still says 1.1mm the past 24hrs, so when it stops raining, i'll take it apart and make sure its tiping ok, also I might try it on the oil tank, and will be getting some rain x in a few days.

So if all that fails I'll bin the stupid thing :grin:

Offline SlowModem

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Re: Rain gauge might not be right
« Reply #12 on: May 14, 2010, 07:19:33 AM »
Well it deff not working right, cos its been raining on and off all morning and it still says 1.1mm the past 24hrs, so when it stops raining, i'll take it apart and make sure its tiping ok, also I might try it on the oil tank, and will be getting some rain x in a few days.

So if all that fails I'll bin the stupid thing :grin:

If you want to be sure of your accuracy, get a 4" gauge to compare it to (Many of us here do that).
« Last Edit: May 14, 2010, 09:06:44 AM by Slow Modem »
Greg Whitehead
Ten Mile, TN USA

Offline killwilly

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Re: Rain gauge might not be right
« Reply #13 on: May 14, 2010, 08:46:35 AM »
Phil, you don't say where in the UK you live. One thing I have noticed is that rain here in Lincolnshire is accompanied by prevailing winds. Last week we had a couple of sharp showers whilst the wind was quite strong, my Vantage Vue recorded nothing, but it is set 22 feet above ground level, not ideal, but I have no alternative.

Make sure your rain sensor is not shielded by trees or buildings.

Alan
Alan

Offline phil2010

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Re: Rain gauge might not be right
« Reply #14 on: May 14, 2010, 10:14:38 AM »
Ive just made it tip a few times by pouring water into it so its working, but it takes quite alot of water to tip it. 1.1mm is never that much water surely? and why is a tip 1.1mm, not 1mm??

Im from the united kingdom, shropshire. Heres a pic where the gauge is and without the box in the way of it now, moved that last night .If you look closely, you'll see my wind sensor at the top left....




Offline 4wd

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Re: Rain gauge might not be right
« Reply #15 on: May 14, 2010, 12:41:32 PM »
Where are you seeing 1.1mm?
It seems odd if it says that on it's console when it only counts 1mm each tip.
I think it's unlikely to be wrong if your test shows a count each time you saw/heard it tip.
The recent showers haven't amounted to much generally.

You just need be patient - coming up to thunderstorm season when you will get some really interesting results especially from those night storms when you aren't sure how heavy it's raining out there.
I started weather recording with something similar and my Dad became quite fascinated with watching it clicking up on wet days.

Offline phil2010

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Re: Rain gauge might not be right
« Reply #16 on: May 14, 2010, 02:04:23 PM »
The first tip read 1.1mm, then the 2nd tip should reads 2.2mm, but it only reads 2.1. Im guessing Ive manual tipped it with water 6 times, as its reading the last 24hrs is 6.4mm, But why the .4??

But yeah I just have to be patient I guess, but I will still buy "rain x" and polish it on the funnel.

Offline 4wd

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Re: Rain gauge might not be right
« Reply #17 on: May 14, 2010, 03:06:50 PM »
I'd be inclined to reset the totals to zero since you  bumped it up anyway - even do a hard reset by pulling the batteries, then just leave it be.
It'll rain Sunday for sure  =D>
I used to reset mine manually at the start of each month (if I remembered...)

Offline phil2010

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Re: Rain gauge might not be right
« Reply #18 on: May 14, 2010, 04:12:00 PM »
Yeah Im gonna do a hard reset at 12 tonight if I remember, for some reason the clear memory for the rain wont work :?

I guess the 1.1mm thing maybe its adding a bit extra, cos Im guessing you loose some rain as its tipping, if you get what I mean?

Offline phil2010

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Re: Rain gauge might not be right
« Reply #19 on: May 14, 2010, 04:21:47 PM »
Oh yeah, where do you get your info from the net of the daily rainfall, because Ive search the net and I cant fine a site with the daily rainfall for my area?

Thanks guys for all your help.
« Last Edit: May 14, 2010, 04:25:54 PM by phil2010 »

Offline 4wd

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Re: Rain gauge might not be right
« Reply #20 on: May 14, 2010, 05:17:55 PM »
If it's the same model I think it is, press reset briefly once, the display should show something about "since". This only shows briefly, while it is there press and hold reset again to go back to zero.

Offline phil2010

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Re: Rain gauge might not be right
« Reply #21 on: May 14, 2010, 06:06:28 PM »
If it's the same model I think it is, press reset briefly once, the display should show something about "since". This only shows briefly, while it is there press and hold reset again to go back to zero.

Ah,, the rest button does a hard reset,, was only trying to reset the rain part,, but the instructions todo this dont work..
..................................
To reset the past 24 hours rainfall:
1. Press SELECT to navigate to the UVI / Barometer /
Rainfall Area. will show next to the Area.
2. Press MODE repeatedly to select Rainfall display.
3. Press and hold MIN / MAX to reset the rainfall to
‘0’.
...........................................

The only downside to my weather station (WMR80) is, my old station had both outside and inside temps on display, but this 1 you have to switch between the outside and inside temps. I like all the info to be displayed without pressing buttons.. Also you should be able to select if you want it to display the past hr or 24hrs of rainfall too, but when you change it to the past 24 hrs, about 5secs later it goes back to hourly rainfall.
« Last Edit: May 14, 2010, 06:08:10 PM by phil2010 »

Offline phil2010

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Re: Rain gauge might not be right
« Reply #22 on: May 15, 2010, 11:04:07 AM »
Another quick question guys, my funnel is held on by 2 screws, should I put any oil on the screws to stop them rusting up, because I need to remove the funnel to get to the batteries??

Offline killwilly

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Re: Rain gauge might not be right
« Reply #23 on: May 16, 2010, 01:34:06 AM »
I think the two screws holding the funnel to the main body are stainless steel, be careful with lubricants they can attract dust and grime making things worse.

Alan.
Alan

Offline killwilly

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Re: Rain gauge might not be right
« Reply #24 on: May 16, 2010, 01:57:29 AM »
Oh yeah, where do you get your info from the net of the daily rainfall, because Ive search the net and I cant fine a site with the daily rainfall for my area?

Thanks guys for all your help.

Not sure how far you are from Shawbury, but their annual rainfall to date is 229.5mm. Check the link below and you will find other local stations to do a comparison.

http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=IENGLAND156

Alan.
Alan