"Roy Avis" wrote in message
...
Thanks, Philip, I didn't realise that it was so widespread a problem.
I would like to point out that I only measure rain in the 5" one a week.
Do you think that, besides the turbulence problem, there could be some
systematic errors in reading small amounts in a 5" measuring glass?
--
Probably, but not very much ... I think Bernard may have explored
this idea. You can also lose a little by evaporation, but for most of
the year in the UK the losses from a standard gauge/bottle would
be very small in a week. During hot and sunny weather, though,
such a loss would probably be significant. (This has probably been
measured in the past but I can't lay my hands on any references just
for the moment).

A standard gauge actually catches marginally less than the
true rainfall of a particular location (calculated using gauges
flush with the ground, surrounded by an anti-splash grid) but
only by, I believe, a couple of percentage points at all but the
most exposed sites.

Philip