[Weather] dual drains -- was Re: conversion help

[claude felizardo]

Mark J wrote:

[snip]

> Yes. And I for one am trying to record some idea of what's actually
> happening, and the tipping bucket doesn't do it at all well except for
> steady conditions within its design limitations. In that previous
> thread I suggested an upper limit of 300mm/hr (laCrosse), and I'm
> happy that at that rate, over one hour, I will record close to
> 300mm/hr and will get a cumulative total of near 300mm. But rain's
> never like that...
>
> This morning was typical: I knew it was raining because my
> conservatory roof was shouting it to me in the dark, but the raingauge
> count didn't move, and it hasn't moved since; officially, it hadn't
> rained, but tell that to the postman...
>
> This type of design has two weaknesses: the funnel, and the bucket :-)
>
> The funnel needs to be very large to record light rain, and very small
> to record heavy; it needs to deliver every tiny drop to its tip
> without beads of water hanging all over its surface, and none should
> splash out - and it needs to deliver it without delay, lest rainfall
> rate be distorted, but not so fast as to impart KE, lest rainfall rate
> be distorted...
>
> The bucket's a design disaster. We know that. It's insensitive to
> light rainfall, and gets overwhelmed with heavy; and rainfall rate
> measurement is in conflict with that of total rainfall. The last is
> easy: use a measuring cylinder. The former is not so easy, as it
> involves mass per units of time or time per units of mass; counts per
> minute or minutes per count. Instantaneous measurement is not
> possible, but is inferred; mm/hr, but for how long? Over one hour,
> very good; but the rain might have stopped long since, and the peak
> was missed...
>
> It needs fresh thought, and no; I haven't any sensible suggestion
> either :-)
>   

So what about two separate sets of rain gauges?    One designed for 
light rainfall, the other for down pours.  Then possibly subtract the 
light rainfall measurements from the downpours?  I suppose you'll still 
have the unknown amount sitting in each bucket...

claude