Cumulus Support

Just a note that I've been playing with a new weather instrument. It can be utilized as a rain tipping bucket only much more sensitive.

It uses the same principal as automatic windshield wipers with a glass / rain switch device.

I'm testing one right now with a 1-wire Hobby Boards dual counter.

http://www.rainsensors.com/

Very interesting.

Although it can be set to all sorts of resolutions (for emulating rain bucket) they do say:

Accuracy and the RG-11
Not as accurate as a properly maintained Tipping Bucket, but a better choice for many applications.
The RG-11 totalizes a statistical phenomenon, so we do not specify an accuracy limit. Sometimes the RG-11 will read a bit high, and sometimes a bit low, and most of the time these readings will be within 20% of the readings from a tipping bucket. Over a long period of time these generally average out.

But as it gives a relay o/p and if you have a power supply ... it does seem to remove nearly all the problems of maintaining a rain bucket, plus it's immune to wind shake etc.

More here: http://www.rainsensors.com/tipping_bucket.php

Keep us upto date of any comparissions you make with your existing sensors please.

Hi

I now have my RG11 set up running with an EL-USB-5 data logger. I have to praise Hydreon who supplied the RG11 - it arrived from the States four days from my order even using the standard US mail.

No data yet as it is still sunny but rain is expected tomorrow.

I've set the 'bucket' to 0.2 mm and I'm using an Excel model to analyse hourly/daily/monthly totals. I wonder how it will compare with the FO rain sensor. Maybe a standard manual gauge would be a good idea as well.

Regards

Alan

Hi

I have had a couple of occasions when the new RG11 gauge has shown 0.2mm in an hour but nothing on the FO gauge - not surprising as the FO uses 0.3 mm however a RG11 0.4mm also did not show on FO so I do wonder if very light rain just sticks to the FO 'funnel'.
The pic shows the RG11 mounted on my WIFI Yagi mast.
Regards
Alan

If it's not windy or warm enough for evaporation it may be the other way around. ie. droplets sitting on the sensor dome. Perhaps one of the instances where it can read upto 20% high.

Ask the manufacturer which circumstances cause high / low variations.

When I first read about the RG-11 some months ago I thought it would be the ultimate replacement for all types of rain gauge. However, after reading various comparisons from several sites it appears the tipping bucket still has the upper hand.

Here's one site I've been following with varying results.
wxforum

Duke

Hi

Over the last few days we have had quite a lot of rain. I have set up a container in an exposed part of the garden as a manual rain gauge and since midday on 4th June it has recorded 49.15 mm against the RG11 at 49.2 mm. The FO tipping bucket over the same period registered 35 mm. More time is needed but first results look promising.

Regards
Alan

Alan, it appears, as also reported in another forum, that the 'Hydreon Optical Rain Sensor' (model RG-11) can indeed produce results that are close to those produced by a high quality tipping bucket rain gauge. Nice to know. Please keep monitoring and reporting on regular basis.

apenwith wrote:Hi

Over the last few days we have had quite a lot of rain. I have set up a container in an exposed part of the garden as a manual rain gauge and since midday on 4th June it has recorded 49.15 mm against the RG11 at 49.2 mm. The FO tipping bucket over the same period registered 35 mm. More time is needed but first results look promising.

Regards
Alan

They are indeed interesting and promising results. Without meaning to be rude, how accurate is the "container" calibrated as a rain gauge?

Duke

Hi

The container is 13 cm diameter and the contents were poured into a 5 cm vessel to expand the measured depth (ratio of the surface areas). Having said that the readings probably were not as accurate as they should be. In the strong winds we've had there may also have been some spray from nearby trees on the Rg-11. The Hydreon offer of a free unit (well almost after customs and post office charges) meant I now have a second RG11 which I am going to site on a flat roof well away from any chance of spray. I have ordered a manual rain gauge to try to get more accurate comparisons.

So we'll see over the next few weeks.

Regards
Alan

Hi
I now have the second RG-11 installed
My good friend Ole has written a very nice recording routine and the manual gauge is also set up.

Watch this space

Regards
Alan

Alan, thank you for the continued updating - it is really appreciated.

Reading again the thread over at wxforum, I see Brian (weather display) has managed to add support for this sensor into WD. I'm not sure if this is an actual measurement from the device or a simple "is it raining yes / no".

Would this type of integration be possible for Cumulus? At least as an early rain indication before a TB tip?

Duke

Duke, only if Cumulus was able to read (use) data from a relay closure - the Hydreon RG-11 Optical Rain Sensor also needs 50 ma of AC or DC power.

I think Brian's software (Weather Display) is reading the data from the RG-11 either using his 1-wire software adapter or through a COM port.

@ Alan, the recording routine you mention, are you recording via PC?

@ Ray, I shall research the "1 wire" system you mention. My knowledge of WD is 0 .

Duke