Rain Gauge Funnel Multiplier

Mark19 · Post by **Mark19** » Tue 19 Oct 2010 6:13 pm

Hi,
I have just added a bigger funnel to my W-8681 rain gauge, and now I need to know what the multiplier should be.
My funnel has a diameter of 18cm, so I have worked out the area is 283cm squared. How would I go about working out the new multiplier?

Thanks,
Mark

Gina · Post by **Gina** » Tue 19 Oct 2010 6:29 pm

The area of the original rain gauge is 55 sq. cm. so the correction is 55 divided by your new funnel area.

Diameter = 18cm Radius = 9cm r2 = 81 - multiply this by Pi (3.142) gives 254.5 sq. cm. So the ratio is 4.627 (254.5/55) and the correction factor (multiplier) is the inverse of this = 0.216. Actually 55/254.5 ie. old/new catchment area.

Mark19 · Post by **Mark19** » Tue 19 Oct 2010 6:36 pm

Thanks alot for that Gina. I never would have worked that out.

Gina · Post by **Gina** » Tue 19 Oct 2010 6:43 pm

Mark19 wrote:Thanks alot for that Gina. I never would have worked that out.

Maths was one of my best subjects at school

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Rain Gauge Funnel Multiplier

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Re: Rain Gauge Funnel Multiplier