Weather Station Hardware > The WxTech Dream Machine

Rainfall intensity

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SLOweather:
A few years ago, I developed an experimental rainfall intensity device using a microphonic Lexan plate transduder I built, the sound card input on a PC, and a strip  chart recorder program called Radio SkyPipe. It works pretty well and it was interesting to watch the bands of rain pass by on the chart.

The original thread is here: http://www.wxforum.net/index.php?topic=1428.0

I know of no PWS that has any sort of indication or measurement of "live" rainfall intensity. They all work "in arrears" determining intensity based on rain gauge tipper timing, and we all know how long it can take between tips, and how rapidly perceived ran rates can vary.

Yesterday afternoon, I got to thinking about the Hydreon RG-11 Mode 6- Drop Detection. From the manual:


--- Quote ---The RG-11 may also provide drop detection. Use this if you want to
do your own, external data interpretation. The output will pulse
once with each detected drop. Normally, it will produce longer
pulses (in multiples of 200 mS) for larger drops. If set to multiple
pulses per drop (SW 3 ON), each detected drop will generate one
or more 100 mS pulses, depending on drop size.
In sensitive mode, the threshold for drop detection is lowered to
below the normal level. This makes the system more sensitive, but
raises the possibility of false detections. It is up to the system
designer to determine the proper tradeoff. Similarly, the Hi drop
threshold will provide an output only for large drops, making false
detections unlikely, for installations were a false detection is
especially objectionable.
--- End quote ---

It seems to me that the Dream Machine could easily monitor the relay output of an appropriately programmed RG-11 and integrate the drop detections into a qualitative,  real-time rain intensity.

Bushman:
Such devices do actually exist, although having never heard of one either, I did have to search for it.

The Laser Precipitation Monitor (LPM) manufactured by Thies is a Present Weather
sensor based on an optical disdrometer. Thus rainfall amounts can be derived from the
disdrometric information. The factory calibration process for the volume measurement
is described and the resulting measurement uncertainty is given.

http://www.thiesclima.com/disdrometer.html

BTW, it will also do snow!  ;)

Weather Display:
I do know of one person using the
http://www.rainsensors.com/
and connected to a 1 wire counter, and having WD read that
then WD knows as soon as rain starts, and so can set the current weather conditions to rain

Bushman:

--- Quote from: Weather Display on November 16, 2011, 02:56:10 PM ---I do know of one person using the
http://www.rainsensors.com/
and connected to a 1 wire counter, and having WD read that
then WD knows as soon as rain starts, and so can set the current weather conditions to rain

--- End quote ---

But that is not intensity.  For that you need a disdrometer.

Weather Display:
intensity could be deduced by the frequency of the detected drops->tips->counts
by applying time

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