Topic: VP2 rain calibration after new rain collector cone

[CloudyDave]

I've been readin topics for the last three hours and can't find an answer.  I recently installed the new rain collector cone from Davis.
Finally came to the conclusion that my reported rainfall from my VP2 is way off from the cocorahs/stratus gauge.  After checking my tipping, I discovered that they were not tipping equally.  Based on info here I used a syringe to measure and inject 5.4 ml of water into my tipping buckets.  One was off by about .8 ml.  So adjusted and now they are equal.  5.4ml for one tip on each bucket.  However.  I was curious and said ok if the bucket holds .01 of rain per 5.4 ml lets put 5.4ml into my cocorahs/stratus gauge.  It was nearly .03 hundreths.  It took about 16.2 ml (3 syringe fills) to equal .1 on the gauge. It should have been .03 hundredths!  FYI.  the syringe is a medical prescription syringe for dispensing 5ml of cough syrup.  Assume it's accurate.  As you can see the math doesn't add up here.  Why am I confused?   

[CW2274]

Because the Davis is 6.5" in diameter, whereas the Coco is 4".

[CloudyDave]

Thanks for the feedback.  Ok, bigger diameter means more water will be collected for the larger surface area.  However it's funneled into a graduated container that takes the diameter into consideration for the mathmatical calculation used to design the inner container.  If one tip on vp2 is .01 and the cocorahs says .03 than one of them is not reflecting the correct amount of water!  Or another way the inner tube is graduated in tenths and hundredths of an inch.  If the water level is at the .01 level than the markings on the container should reflect a true .01 water level.  So if I took the contents of one tip of the vp2 which is supposedly .01 of water and dump that into the cocorahs it too should show .01 not .03.  Yes / No???

[Bashy]

Its not about the inner tube as such or the outer for that matter,
Its all about the diameter of the opening, the collection area, its that that is smaller than the davis
collection area, ignore the tubes, look at the collection area itself (opening)

PS, dont get confused with ML and MM either

[dendrite]

Because the Davis is 6.5" in diameter, whereas the Coco is 4".

Adding the areas onto this...

6.5" Davis: ~33.2sqin
4" Stratus: ~12.6"sqin

That's about a 2.6:1 ratio right there. So 0.10" put into the Davis should give you about 0.26" in the Stratus assuming those diameters are exact. I haven't actually directly measured their diameters even though I own both.

[CloudyDave]

It must have been the drugs I was on last night.  I get it finally.  It's a measure of rainfall.  Not a liquid volume measure.  Whew!  I don't know why I was thinking they should be the same measure of liquid.  Thanks all! 

[CW2274]

It must have been the drugs I was on last night. 

Love your honesty!

[PaulMy]

And here you can get prescription for all your weather ailments!


Enjoy,
Paul