Cumulus Support

hills wrote:I haven't read the whole thread, but if the first post is still up to date then I've broken the Highest minimum:

Highest Minimum 28.1 °C on 31 January 2011

I update records when I notice them but if anyone thinks I have missed theirs then please do PM me - Thanks

hills wrote:I haven't read the whole thread, but if the first post is still up to date then I've broken the Highest minimum:

Highest Minimum 28.1 °C on 31 January 2011

Beat you! 28.5 C for highest minimum.
Also, I have records for inside temp....
Highest Inside 35.3
Highest Low inside 31.8
You'll need to be tough to beat those, as you'll be tempted to put the aircon on!

ag0044 wrote: Hourly rain: 37.5mm at 16:50 on 20 April 2010
Daily rain: 89.1mm at 08:43 on 21 April 2010

[I can loosely verify the daily rain total, as our old-style manual rain gauge filled up, was emptied - I was silly enough to go out into it - and nearly filled up again.]

I can beat that:
Hourly rain: 67.3mm (see pic nest post)
I did beat your Daily at 90.8mm but can't beat 231.3mm! (not yet at least)

captzero wrote:

mynameis wrote:Highest monthly rain : 237,7 mm july 2009 - Sweden

That only just beats my Daily rainfall.
Highest Daily Rain: 231.3 mm on 11 October 2010
Wettest month - 476.1 mm, October 2010

I beat the wettest month @ 606mm.
Also I see Steve says that the rain rate is calculated differently and thus Davis naturally get a higher rain rate compared to Fine Offset.
So, for Fine Offset, High Rain rate 121.1mm/hr.
Sorry, wrote on the picture as a WH....it's a WS-1081 Fine Offset (Sinometer).

Record for most rain days in a month: (and it's only my 2nd month of records)
24 in January 2011.

MickinMoulden wrote: So, for Fine Offset, High Rain rate 121.1mm/hr.

Beat that (just) in dry Karoonda:
Highest Rain Rate 131.9 mm/hr at 4:34 PM on 07 December 2010

But it didn't last for long:
Highest Hourly Rainfall 26.4 mm at 5:24 PM on 07 December 2010

Bob

tjaliwalpa wrote:

MickinMoulden wrote: So, for Fine Offset, High Rain rate 121.1mm/hr.

Beat that (just) in dry Karoonda:
Highest Rain Rate 131.9 mm/hr at 4:34 PM on 07 December 2010

But it didn't last for long:
Highest Hourly Rainfall 26.4 mm at 5:24 PM on 07 December 2010

Bob

Ah...well done Bob, I know I'm gonna beat that since I've only been going a month. I'm attaching a 24hr chart of the rainfall rate so that maybe we can compare our Ws-1081 to the Davis Pro's and others. It seems the DP get really high readings that Steve seems to understand. Any one with a DP with a high rain rate care to supply a graph. Is a 24hr graph to long? Should we make it 1 hr, what do you think?

MickinMoulden wrote:It seems the DP get really high readings that Steve seems to understand. Any one with a DP with a high rain rate care to supply a graph. Is a 24hr graph to long? Should we make it 1 hr, what do you think?

The main difference between the Davis rain rate (as calculated by the station) and the FO rain rate (calculated by Cumulus) is the period over which the rate is calculated. The Davis rain rate is calculated using the time between adjacent tips, and so a very brief (less than a minute), high intensity shower can produce a very high rain rate. The Cumulus rate is simply the average over the last five minutes, so requires a more sustained level of rainfall to achieve similar rates.

The rate from a Davis can change (up and down) so quickly that it may not even register on the 1-minute sampling period of the Cumulus graphs, or retrospectively, looking at data from the logs. For example, my all-time high rainfall rate as measured by my Davis is 295.4 mm/hr at 17:18 on 24th March 2009. Here's the graph plotted from my logs at that time. Not very impressive.

steve wrote:

MickinMoulden wrote:It seems the DP get really high readings that Steve seems to understand. Any one with a DP with a high rain rate care to supply a graph. Is a 24hr graph to long? Should we make it 1 hr, what do you think?

The main difference between the Davis rain rate (as calculated by the station) and the FO rain rate (calculated by Cumulus) is the period over which the rate is calculated. The Davis rain rate is calculated using the time between adjacent tips, and so a very brief (less than a minute), high intensity shower can produce a very high rain rate. The Cumulus rate is simply the average over the last five minutes, so requires a more sustained level of rainfall to achieve similar rates.

The rate from a Davis can change (up and down) so quickly that it may not even register on the 1-minute sampling period of the Cumulus graphs, or retrospectively, looking at data from the logs. For example, my all-time high rainfall rate as measured by my Davis is 295.4 mm/hr at 17:18 on 24th March 2009. Here's the graph plotted from my logs at that time. Not very impressive.

Pomona - pomona_2011-02-02_12-35-39.png

On the graph it measures to 7. Is that 7 inches per hr (177.8mm/hr)?
Also, could you add the rain amount with your graph, I think it may help to compare. I actually used a ruler to get the steepest gradient from the rain being recorded, and my measurements mirrored what was recorded for the rain rate.

MickinMoulden wrote:On the graph it measures to 7. Is that 7 inches per hr (177.8mm/hr)?

No, it's millimetres!

Also, could you add the rain amount with your graph, I think it may help to compare. I actually used a ruler to get the steepest gradient from the rain being recorded, and my measurements mirrored what was recorded for the rain rate.

Here's the graph with the rain total included. It was only a small amount of rain, but it fell very quickly. Because of the 5-minute logging interval, the gradient isn't steep, but presumably at some point it was falling very heavily for a short period, hence the high rate.

steve wrote:

MickinMoulden wrote:On the graph it measures to 7. Is that 7 inches per hr (177.8mm/hr)?

No, it's millimetres!

Ha Ha That's funny. Imagine what I would (and others with a FO) would have recorded with a Vantage Pro? At least with the Cumulus Graph we can compare apples with apples.
I can tell you when it rains here when your driving, and hard, you have to halve your speed (ok we should actually pull over) because you can only see the car in front of you for the 1/2 second after the wiper blades sweep past. Even with the other cars headlights/tail lights on, all the cars dissapears from view (this is during the middle of the day).
Actual visability would be 100 to 200 meters if you're standing on your varandah.

Ha Ha That's funny.

But the 7 doesn't really mean anything, it's just the figure that the rate had got down to at the point where Cumulus took its snapshot. Had I been logging at 1-minute intervals, then the 295.4 figure may well have appeared in the log. This just demonstrates the deficiency in Cumulus 1 of its 'snapshot' style of logging.

MickinMoulden wrote:Imagine what I would (and others with a FO) would have recorded with a Vantage Pro?

It's hard to say; possibly exactly the same as you have recorded now. It's not simply a case of saying that the Davis rate is always higher than the Cumulus FO rate. You just need a shorter period of heavy rain with a Davis to get a high rate.

Here's my humble contribution:

Max Rain Rate : 5 Jan 11 - 225.8 mm/hr

The best you can do with an FO station is a reading every 48 seconds. I've definitely seen quick bursts of rain lasting for shorter periods.

steve wrote:

Ha Ha That's funny.

But the 7 doesn't really mean anything, it's just the figure that the rate had got down to at the point where Cumulus took its snapshot. Had I been logging at 1-minute intervals, then the 295.4 figure may well have appeared in the log. This just demonstrates the deficiency in Cumulus 1 of its 'snapshot' style of logging.

I can fully understand what you are saying, however, how is it you can say the above that it

the 7 doesn't really mean anything, it's just the figure that the rate had got down to

(from 295 to 7) then......

MickinMoulden wrote:Imagine what I would (and others with a FO) would have recorded with a Vantage Pro?

It's hard to say; possibly exactly the same as you have recorded now. It's not simply a case of saying that the Davis rate is always higher than the Cumulus FO rate. You just need a shorter period of heavy rain with a Davis to get a high rate.[/quote]
.........you say that mine would be excactly the same even if I had a VP? Mathmatically it is "possible", however you can get 295 on your VP but Cumulus says 7 but yet you can't believe that mine at 121 couldn't be extremly higher on a VP let alone any different.
Let's forget what both our rain rates are for a minute. You register 0.6mm at some point in 5 minutes, then 0, then 0 then 0.2mm at some point in 5 minutes. I on the otherhand got 7mm at some point in 5min, then 7, then 3 then 3 then 10.1. Which would you think had the heaviest rain rate? You measured 0.6mm in 5 min and at some point got 295.4mm/hr, or the equivalent of 0.6mm falling in 7.3 sec and I had 10.1mm fall at some point in 5 minutes, yet you find it hard to believe that if I had a VP recording the rain rate that it wouldn't be higher than 295, and go on to say that it be "possibly exactly the same".
But we will never know.
As we are all Cumulus users, my point was, that using the Cumulus graph is the only way we can compare fairly and I believe that it should be noted that VP and others PWS should have their separate records.