Bigger Rain Gauge?

[Hairy Celt]

My new weather station came with a rain gauge of about 10cm diameter. It records nothing in short showers. Would it be possible to put a large funnel on the top to increase its 'catchment'? Anyone done this?

Edited January 16, 2006 by Hairy Celt

[Terminal Moraine]

My new weather station came with a rain gauge of about 10cm diameter. It records nothing in short showers. Would it be possible to put a large funnel on the top to increase its 'catchment'? Anyone done this?

You don't mention, H.C, whether it's an automatic station or a manually read gauge, no matter, the end result is the same.

If it's an automatic station the electronics should be calibrated to a 10cm catchment funnel, if not your readings would never be comparable with those from any standard gauge which has a funnel diameter of 5" or 127 mm.

If the gauge is one of the manually read type the measuring jar will be calibrated to a 10cm diamter gauge and simply adding a larger funnel will render any readings inaccurate.

It's possible that the failure of your gauge to record anything in short showers is not due to the 10cm diamter funnel but due to either the siting of the gauge or the duration of the showers.

Is the funnel sheltered by any tree, building, bush etc or is it mounted on a post?

Any of the above will reduce the catch of the gauge, possibly by a very large amount. If a shower is very light or very short it's quite possible for there to be nothing in the gauge as not enough rain has fallen to register. A rough guide to whether or not rain is measurable is when it just begins to drip from surfaces such as roof tiles, shed roofs etc. If roofs etc begin to drip you should have measured something.

Lastly, what is the minimum amount your gauge is calibrated to read? If it's 0.1mm then the above applies, if it's 0.5mm you would need more than a light shower to register anything.

T.M

[I can't believe it's not better]

4 Inches! That's pathetic. I would definitly want to increase my catchment area, if possible. The problem might be how much rain sticks to the collector material though. I was thinking of a Teflon coating - but I heard there's an even better material! :huh: Dunno.

[optrex]

My new weather station came with a rain gauge of about 10cm diameter. It records nothing in short showers. Would it be possible to put a large funnel on the top to increase its 'catchment'? Anyone done this?

Hairy,

I've got an OS928 that has a 10cm gauge. It records 1mm bucket tips. By increasing the area x4 through use of a 20cm funnel and making the relevant adjustment in the software program for gain, I now have a 0.25mm bucket tip. A couple of the members on the Midlands Weather Webring have done similar conversions and all seem to be working accurately.

Edited January 23, 2006 by optrex

[Hairy Celt]

Thanks for the advice everyone. It's in a suitable place, so that's not a problem. Yes, this one's an OS928 and records in 1mm increments. Not really sensitive enough. I'll have a look in the shops for something bigger - polycarbonate has a good finish... Optrex, is it Weather Display you use?

[optrex]

No I use virtual weather station, but you can make the same "gain" adjustment in WD just mark it down to 0.25 instead of 1.

Using a standard plastic funnel we dont have issues with rain sticking to the collector material. If you did you coudl try coating it with rainex or silicon spray, but I really don't think you will need it.

[Hairy Celt]

No I use virtual weather station, but you can make the same "gain" adjustment in WD just mark it down to 0.25 instead of 1.

Using a standard plastic funnel we dont have issues with rain sticking to the collector material. If you did you coudl try coating it with rainex or silicon spray, but I really don't think you will need it.

Right, I'll do this. (No great rush though - the forecast isn't exactly rainy, is it?)

Edited January 24, 2006 by Hairy Celt

[Hairy Celt]

Ho ho ho just glued a 30cm diameter funnel to it, and recorded 0.3mm of rain in a passing shower. In business

[Osbourne One-Nil]

Am I missing something here? Alter the circumference of the collector and you're altering the volume of water collected and the callibration goes to cock.

Just re-read TM's comments. Ignore me.

[Hairy Celt]

Am I missing something here? Alter the circumference of the collector and you're altering the volume of water collected and the callibration goes to cock.

Just re-read TM's comments. Ignore me.

It's Optrex's post, #4, that explains it. TM's earlier post doesn't.

[Scribbler]

I guess that my question comes into this context – please will someone tell me the answer?

When we have a good frost or a heavy dew around here, our local weather station usually shows 0.3 mm of rain (precipitation).

Does this actually count towards annual or monthly rainfall figure?

Not having an automatic set-up (yet) I’m just curious.

[Hairy Celt]

I guess that my question comes into this context – please will someone tell me the answer?

When we have a good frost or a heavy dew around here, our local weather station usually shows 0.3 mm of rain (precipitation).

Does this actually count towards annual or monthly rainfall figure?

Not having an automatic set-up (yet) I’m just curious.

My guess is that yes it would count, but if you were a scrupulous recorder, you would enter a note for that day to say it was frost/dew rather than rain. But there are better qualified folk here than me :blink:

[Cloudburst]

I guess that my question comes into this context – please will someone tell me the answer?

When we have a good frost or a heavy dew around here, our local weather station usually shows 0.3 mm of rain (precipitation).

Does this actually count towards annual or monthly rainfall figure?

Not having an automatic set-up (yet) I'm just curious.

There was another post asking about whether Dew/Forst prep. is counted as rainfall and the conclusion was yes. :blink:

[Scribbler]

Thanks Cloudburst

Missed the previous one so ta for your comments.

I reckon that's a bit unfair.

Makes me wonder how much extra 'precipitation' is recorded in seaside town as a result of seagulls s****ing in the collectors. :blink: