wind gust = wind speed

[Paragon]

Hello
I have a Davis Vantage Vue with Cumulus 1.8.9.930. I notice that the wind speed gauge shows, for example, speed 7 kph, green band up to 11.3 kph, red band up to 24.3 kph. The data being stored is 29/05/10,09:30,11.3,86,9.2,11.3,22.5,249,0.0,0.0,1011.38,207.0,18.2,57,9.7,10.0,11.3,
which seems to show that the wing gust and average speed are being confused. The wind gust graph also plots more or less on top of the average wind speed graph too, which can't be correct.

Ref the bottom (wind rose gauge), can you expand on how to read it please? I have seen other wind roses that use a circular stacked bar chart, with the length of bar being % of time from that direction (i.e. the dotted circles) and the colours within the stack being the speed from that direction.

One more question: I am struggling to understand the logging intervals. I have asked for 5 minutes. I am getting half an hour when I plug in and down load, then 5 minutes while connected. The download this morning was at about 8:53 or so, the last stored data set was at 06:00, the next at 08:55. What do I need to set to fix this please?

Thanks for your help.
Graham, Tauranga

[steve]

I have a Davis Vantage Vue with Cumulus 1.8.9.930. I notice that the wind speed gauge shows, for example, speed 7 kph, green band up to 11.3 kph, red band up to 24.3 kph. The data being stored is 29/05/10,09:30,11.3,86,9.2,11.3,22.5,249,0.0,0.0,1011.38,207.0,18.2,57,9.7,10.0,11.3,
which seems to show that the wing gust and average speed are being confused. The wind gust graph also plots more or less on top of the average wind speed graph too, which can't be correct.

From the help, this is what the gauge is supposed to be showing:

"The wind speed indicator shows three values; the needle shows the current snapshot of the wind speed, as read from the weather station. The green arc shows the current ten-minute average wind speed, and the red arc shows the recent highest gust (in the last ten minutes)."

These corrsepond to the values on the main display as follows:

Needle: Latest
Green: Average
Red: Gust

Comparing these values to the console, 'latest' is the 'speed', and 'average' is the 10-minute average. My VP2 doesn't have an equivalent of the Cumulus 'gust' (i.e. the peak value in the last 10 minutes), but someone recently seemed to suggest that the Vue does.

Regarding your data log, you have average=11.3, recent high gust=22.5, and a latest=9.7. These all seem consistent and reasonable. Your confusion may arise because of the Cumulus terminology for the various values; it works with a number of different weather stations, each one supplying different measurements, and I have to try to make the Cumulus display fit with all of them.

Regarding the graphs; this depends on what you have for this setting, in the display configuration:

"Graphs: Plot latest gust. On the wind graph, Cumulus normally plots the highest gust from the last 10 minutes. Selecting this option causes Cumulus to plot the latest 'gust' value from the station instead. The effect of this depends on the type of station you have, and how it generates this 'latest' value; you may prefer it this way, or you may not. Note that changing this does not cause the graph to be redrawn, it just changes the method of plotting from that point onwards."

Hopefully, given all the above explanation, you can now make sense of it all.

Ref the bottom (wind rose gauge), can you expand on how to read it please? I have seen other wind roses that use a circular stacked bar chart, with the length of bar being % of time from that direction (i.e. the dotted circles) and the colours within the stack being the speed from that direction.

The length of the line in each direction is proportional to the 'amount of wind' from each direction (using 16 compass positions by default) in the recent few minutes. The exact time period depends on how often Cumulus is reading data from your station (i.e. it's a fixed number of samples, not a fixed time). The 'amount of wind' takes into account the number of samples from a particular direction and the speed of the sample.

One more question: I am struggling to understand the logging intervals. I have asked for 5 minutes. I am getting half an hour when I plug in and down load, then 5 minutes while connected. The download this morning was at about 8:53 or so, the last stored data set was at 06:00, the next at 08:55. What do I need to set to fix this please?

When 'live' Cumulus logs at the interval you've configured in Cumulus. When downloading logger data, it logs each entry from the logger. So to make them both the same, you need to either change the Cumulus setting, or the logger setting (using the Weatherlink software).

[gemini06720]

...My VP2 doesn't have an equivalent of the Cumulus 'gust' (i.e. the peak value in the last 10 minutes), but someone recently seemed to suggest that the Vue does.

Indeed, on one setting the Vantage Vue displays the wind speed and the wind direction (in degrees); on the other setting, the wind speed as well as the last gust speed and the 10 minutes average wind direction are shown.

[steve]

Version 1.90 of the VP2 firmware also adds the 10-minute gust value; I don't know if there's any way to get it to display on a VP2 console or whether it's only available to software, via the new LOOP2 command.

[gemini06720]

...via the new LOOP2 command...

The same LOOP2 command that has been creating havoc with Virtual VP...

Steve Hatchett has released a modified version of Virtual VP:

I have a beta of VirtualVP, v. 1.2.4 that temporarily addresses the problem of the new Loop command in VP firmware 1.90. If a program asks the console, through VirtualVP what the firmware version is, VirtualVP simply passes along what the console says. But if it's firmware v. 1.90, then the weather program assumes it can use the new loop command, which VirtualVP does not support. This v. 1.2.4 of VirtualVP temporarily addresses this by filtering the response to the version command so it reports an earlier version so the weather program will not assume the loop2 command can be used. The beta is a zip of the exe, which can be extracted and placed in the folder where VirtualVP is installed. The download is here: Virtual VP version 1.2.4.72 dated May 23, 2010.

This will only work for the Vantage Pro (not the Vantage Vue). But I will try and make a similar change for that in the next couple days.

I would like to add native support in VirtualVP for the new loop2 command, but have not gotten my hands on the specs for the command. If anyone has that, I would be thankful if you could email it to me (steve at softwx.com).

Also, a VirtualVP user alerted me to a virtual serial port driver I had not encountered before. It is a fully signed driver, so it can be used on 64-bit Windows without having to jump through any other hoops. The link is on the download page at softwx.com, but to save you having to go there here is this link: VSP Manager Web page. I have not tested it myself, but a couple VirtualVP users have been using it and report that it works well.

Steve

Note: Be advised that before installing VSP Manager 'ALL virtual ports installed by other virtual serial port programs (vCom, com0com, VSPE, etc.) MUST BE DELETED. Then the vsp program(s) themselves MUST BE UN-INSTALLED . This is mandatory as VSP Manager will not recognize them and conflicts may occur'.

[mcrossley]

Thanks for that info about VSP Ray, we use Virtual Serial Ports on some astronomy software I am involved in, and the lack of free (non-commercial use) signed 64 drivers was a real pain involving booting in developer mode etc.

[gemini06720]

Thanks for that info about VSP Ray, we use Virtual Serial Ports on some astronomy software I am involved in, and the lack of free (non-commercial use) signed 64 drivers was a real pain involving booting in developer mode etc.

Mark, if you try/use the VSP Manager in 64-bit mode could you please let us know of the results - it is nice to read from the author/designer that a software can be run in 64-bit mode, but it is better to find out from one of us (the users) has indeed the software was able run and that it has done what it was supposed to do, that is, it has 'operated within normal parameters'...

[Paragon]

Steve, Thanks very much for your response to my questions. I think it all makes sense.

I was using the Select-a-graph. I plotted Wind Gust and Wind Speed. For most of the data (my data only starts on 15 May), they plot on top of each other. It is only since 29 May that I can see they are different. I must have changed something, but I don't know what it could have been. I have attempted to attach the plot...(1st time I have tried it).

There is discussion about the Raining Cats n dogs message on the VV. We have seen it over the last couple of days. The rain rate was about 9.2 or so mm/hr. BTW, we are quite excited here. We had about 6 months with about half our average rainfall (trees are dying), then in the last three weeks we have had 270 mm or so, nearly 70 of them today. Yahoo! It is fun having the rain gauge to keep track of it.

Thanks again for your help.
Graham

[steve]

That does look strange. The only way I know of that the gust can be the same as the average is as described in the FAQ:

http://wiki.sandaysoft.com/a/FAQ#My_.E2 ... ed_values.

But that would mean that all of your data prior to May 29th would have to have come from the logger. But it would definitely fit with your stated 30 minute logger interval.

[Paragon]

Thanks again Steve, I think you are right. I didn't twig that I had to use Weatherlink to talk to the console. 29 May is probably when I reset the console using Weatherlink, to 5 min logging, after your post.

One of the reasons I am interested in the longer term wind rose is that I have a dream of one day perhaps installing a wind turbine, and feel as though I am gathering the data for assessing if it is viable.

Regards
Graham

[steve]

Wind run is probably a good figure to look at for wind turbine viability. It's a measure of the 'amount' of wind that you've had - it's really just another way of looking at the overall average speed.

[beteljuice]

There are a few sites (can't remember offhand) with 'calculators', but if I remember correctly it's more a case of hours of 'useful' windspeed, typically > 9 mph for an effecient turbine.

It's surprising just how few good sites there are ! - I suppose a good rule of thumb would be if you live near somewhere called mill street or windmill lane.

[steve]

Living in Orkney is another good rule of thumb