I originally made my manual rain gauge from a standard size funnel.
Collected in a per-tared aluminium container, weighed on my wife's quite
accurate cooking scales in gms to give the exact volume, did the maths and
by entering in a spreadsheet got what seemed to be quite accurate results.
This could be a bit tedious in the old days when it used to rain here (;-)
so I bought an electronic tipping gauge.This works well and gives good
results but it presumably only tips with every complete whole mm. (This
model). For example it recorded 3mm last night but this could have been
3.9mm. If it rains again soon it will only take 0.1mm to get 1mm recorded.
I'm not particularly bothered because these are not official figures and it
will even out over time (unless of course what is already in the tray
evaporates before the next event, which will lead to an overall low bias).
Incidentally I am using an electronic gauge purchased from
www.conrad-direct.co.uk which is identical to the Oregon RGR122 (comes from
same factory) but only costs £22-00. It is useful in that it keeps a running
total and the last 9 days individual amounts.

Dave

I built a tipping bucket type rain a while ago. 0.5 mm of rain per tip which
activates a magnetic reed switch and it is then logged.

I have an official Met Office funnel type rain gauge which I use for all my
rainfall measurements.

When I compare the two I find that the tipping bucket gauge generally
under-records by about 10%.
_______________
Nick G
Exe Valley, Devon
50 m amsl

Nick G wrote:
I built a tipping bucket type rain a while ago. 0.5 mm of rain per tip which
activates a magnetic reed switch and it is then logged.

I have an official Met Office funnel type rain gauge which I use for all my
rainfall measurements.

When I compare the two I find that the tipping bucket gauge generally
under-records by about 10%.
_______________
Nick G
Exe Valley, Devon
50 m amsl



My knowledge of mechanics is non existent but is it not possible to make it tip
at approx 0.46mm and log 0.5mm, thus making it record more accurately than -10%?


--
Gianna

I've had two 0.2 mm TBRs logged to my AWS for several years now, and
they typically under-record between 1 and 3% compared to my adjacent
Met O standard 5 inch gauge. This is probably about the best one can
expect as these are professional class instruments (both belong to the
Environment Agency) and are regularly calibrated. The slight error most
probably results from some loss due to differences in wetting of the
funnels, and in evaporation of the part-filled bucket contents.

As a matter of interest, three months back I purchased one of the
wireless 1 mm capacity tipping bucket gauges referenced in the first
post on this thread. I hasten to add I use this only for
distant-reading purposes, not climatology! After careful calibration, I
found the 1 mm tip was surprisingly accurate for an inexpensive
instrument (within 4%, which was as accurate as I could measure the
volume of water poured in while I counted the tips). Daily totals show
good agreement with the checkgauge when more than 2-3 mm falls, but
where it loses out are small falls ( 0.5 mm or so), especially a day
or two apart, where they simply evaporate and are lost to the record.

Monthly totals from both gauges compared with my standard gauge have
been (making slight adjustments to bring them all to 09-09h UTC
terminal hours):

March - checkgauge 50.9 mm (=100%), TBR 1 49.7 mm (97.6%), Conrad gauge
40 mm (79%)
April - checkgauge 34.3 mm (=100%), TBR 1 34.3 mm (100%), Conrad gauge
30 mm (87%)

I would recommend one of these little instruments, even if you have an
AWS. They are great for watching thunderstorm rainfall tick up whilst
enjoying the lightning in the comfort of the conservatory, or for a
quick glance on getting up in the morning how much (if any) rain has
fallen overnight. But _not_ recommended for climatological purposes!

Stephen