Author Topic: Calibrating Tipping rain gauge (see-saw)  (Read 345 times)

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Offline Weatherwx85

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Calibrating Tipping rain gauge (see-saw)
« on: July 18, 2019, 02:13:58 PM »
Hi,
I am trying to calibrate my rain gauge, I have started with a 5ml syringe (weighed to confirm 5g water) and have adjusted the screws until it tips at roughly 5.44ml. However to do this I notice the screws are not level, one is all the way down the other is up by a turn or two. The ISS is perfectly level so I know it isnt that. I am currently testing with a water bottle with hole in with 544g (544ml) of water in to see if I get 20mm of "rain". I just wanted to check if the screws should be different or roughly the same with regards to turns. Obviously will see what happens with the current test but thought I would post this while I am waiting :)

Thanks

Offline CW2274

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Re: Calibrating Tipping rain gauge (see-saw)
« Reply #1 on: July 18, 2019, 03:15:05 PM »
I am currently testing with a water bottle with hole in with 544g (544ml) of water in to see if I get 20mm of "rain".
Unless I'm missing something (certainly possible), shouldn't 544ml (which is indeed 1" of rain for a Davis bucket) equal 25.4 mm?

Offline Weatherwx85

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Re: Calibrating Tipping rain gauge (see-saw)
« Reply #2 on: July 18, 2019, 03:17:03 PM »
My math could be wrong

544/5.44ml = 100 tips

100 * 0.2 = 20mm
« Last Edit: July 18, 2019, 03:18:41 PM by Weatherwx85 »

Online johnd

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Re: Calibrating Tipping rain gauge (see-saw)
« Reply #3 on: July 18, 2019, 03:36:55 PM »
IMHO: Forget trying to calibrate buckets with a syringe - there are reasons why this is not a good approach.

DRIP 544ml into the cone steadily/slowly and see if you measure 25.4mm rain - it doesn't then matter whether you have a 0.2mm (127 tips) or 0.01" (100 tips) increment gauge.
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Offline Weatherwx85

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Re: Calibrating Tipping rain gauge (see-saw)
« Reply #4 on: July 18, 2019, 03:37:59 PM »
bugger will start again, was getting 19.8/20.2 mm on a few tests and thought that was correct :(  ](*,)

Offline CW2274

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Re: Calibrating Tipping rain gauge (see-saw)
« Reply #5 on: July 18, 2019, 03:47:12 PM »
IMHO: Forget trying to calibrate buckets with a syringe - there are reasons why this is not a good approach.
As an end-all-be-all, absolutely agree, infinitely too small of a sample size. However, to get the spoons to tip as close as possible to the same amount, I think this is a good way start before moving on to a much larger sample size.