Author Topic: Wind direction when wind is calm  (Read 578 times)

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Offline fkapp

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Wind direction when wind is calm
« on: November 05, 2021, 08:21:33 AM »
I am running Weatherlink Live and am trying to find a solution to how wind direction is reported when wind is calm.
This is set to North using weatherlink live which makes wind direction choppy on weather underground and cwop, etc.

I am trying to find SW that will not default to north when wind is calm.

In reading the Meteobridge release notes I found this which hope someone can clarify how this reports wind when calm using weatherlink live and MB on PI.

"released June 16, 2019
now keeps wind direction for Davis WLL as has been before, when wind speed drops to zero (instead of setting wind direction to "N")."

My question re this note:
Does this mean that when the wind is calm, is the wind direction is sent to upload sites like WU and CWOP as last reported direction?
Or is the wind direction reported as blank?

Thanks so can no longer have the choppy data on light wind days bouncing between N and actual direction
Frank



Offline CW2274

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Re: Wind direction when wind is calm
« Reply #1 on: November 05, 2021, 07:04:10 PM »
I am trying to find SW that will not default to north when wind is calm.

Does this mean that when the wind is calm, is the wind direction is sent to upload sites like WU and CWOP as last reported direction?
Or is the wind direction reported as blank?
I stated here before that having the direction default to north every time the cups stop spinning would drive me nuts. Although I don't use WLL, I do use WL USB and that is not the case, and surprised a Davis product that does. When the wind is dead calm (no movement of the cups), the direction in degrees remains displayed in it's last location. Mesowest and the NWS display a blank for direction when the wind is dead calm, as it should. WU, don't know and don't care. Hopefully WLL has a setting to stop that annoying and worthless feature.

Offline fkapp

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Re: Wind direction when wind is calm
« Reply #2 on: November 05, 2021, 07:21:48 PM »
Agree that is annoying and in my opinon reports bad wind direction data. Hope software can resolve but I tried cumulusmx today and reports 360 degrees when calm.
Disappointed in this data handling by weatherlink live.

North is also sent to cwop when wind is calm too using weatherlink live fyi.

Hope someone can answer how meteobridge reports wind direction when wind is calm using WeatherLink live please.

 Hope it does or may be stuck with this issue unless there is other sw option.  A con of wll though fyi

Offline CW2274

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Re: Wind direction when wind is calm
« Reply #3 on: November 05, 2021, 07:30:49 PM »
North is also sent to cwop when wind is calm too using weatherlink live fyi.
Mesowest and the NWS are CWOP and I do not have that issue.


Offline fkapp

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Re: Wind direction when wind is calm
« Reply #5 on: November 05, 2021, 07:33:56 PM »
That good. Too bad weather link live sends info in way is reported as North.  Should be blank or previous direction with speed but now have this default annoyance to figure out depending what site uploading too.

Hope someone can clarify how meteobridge pi handles so understand please

Offline fkapp

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Re: Wind direction when wind is calm
« Reply #6 on: November 05, 2021, 08:01:44 PM »
Thanks for sharing Mesowest info. I checked my station info and good news is you are correct that they handle the calm wind by not reporting a direction.
https://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=F6381

Was worried because of the Findu data on CWOP where calm is north (see my data here)
http://www.findu.com/cgi-bin/wxpage.cgi?last=24&call=FW6381

Glad Mesowest handles as blank cause didn't want to send erroneous data.

If someone who is using weatherlink live and meteobridge can let me know how calm wind direction is sent to upload sites (north, blank, last direction with speed) would be appreciated.

Thanks
Frank

Offline mcrossley

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Re: Wind direction when wind is calm
« Reply #7 on: November 05, 2021, 08:14:04 PM »
By default Cumulus MX will use the common convention of 360 for North, and 0 (zero) for calm. The WLL uses the same convention.

You can override that behaviour in the station settings and Cumulus will then continue reporting the last valid wind direction when it is calm.
Mark

Offline fkapp

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Re: Wind direction when wind is calm
« Reply #8 on: November 05, 2021, 08:18:24 PM »
Great news. What needs to be changed and where please?
Appreciate the response as have Cumulus running good and am tuning/learning all the settings.

Thanks
Frank

Offline CW2274

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Re: Wind direction when wind is calm
« Reply #9 on: November 05, 2021, 08:27:54 PM »
By default Cumulus MX will use the common convention of 360 for North, and 0 (zero) for calm. The WLL uses the same convention.
Personally, I don't understand that line of thinking. I want to know where the prevailing wind is/was from, not a false direction just because it not currently "blowing".

Offline PaulMy

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Re: Wind direction when wind is calm
« Reply #10 on: November 05, 2021, 10:45:20 PM »

Quote
Great news. What needs to be changed and where please?
You can set that in Station settings => Common Options
Zero Bearing:
    [ x ] Use bearing zero when calm
     Use zero for current bearing if speed is zero

Enjoy,
Paul

« Last Edit: November 05, 2021, 10:54:34 PM by PaulMy »
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Offline Mattk

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Re: Wind direction when wind is calm
« Reply #11 on: November 05, 2021, 11:03:34 PM »
When the wind is calm any direction is meaningless, continuing to report the last wind direction is even more meaningless. For previous conditions then use the pastcast conditions based back in time or averaged progressively back over time should be in the reporting loop. 

Offline fkapp

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Re: Wind direction when wind is calm
« Reply #12 on: November 05, 2021, 11:54:06 PM »
By default Cumulus MX will use the common convention of 360 for North, and 0 (zero) for calm. The WLL uses the same convention.

You can override that behaviour in the station settings and Cumulus will then continue reporting the last valid wind direction when it is calm.

Thanks re the bearing 0 setting. My question is where and how do I override so that the last valid wind direction is reported instead when it is calm?

Frank

Offline CW2274

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Re: Wind direction when wind is calm
« Reply #13 on: November 05, 2021, 11:55:02 PM »
continuing to report the last wind direction is even more meaningless.
I completely disagree. It tells you where the wind came from last at a glance. Is that mind blowing info, perhaps not, but it's damn sure better than showing the last wind direction wrong.

Offline sky_watcher

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Re: Wind direction when wind is calm
« Reply #14 on: November 06, 2021, 02:13:29 AM »
When the wind is calm any direction is meaningless, continuing to report the last wind direction is even more meaningless. For previous conditions then use the pastcast conditions based back in time or averaged progressively back over time should be in the reporting loop.
With a good system that is level and has good bearings, it is possible for the vane to move without there being enough wind for the cups to move enough to compute a wind speed.

Ignoring bird landings and alike, direction changes can show that there is a slight wind/turbulence about, but it is lower than the minimum speed that can be calculated from the cups. I don't see the sense in throwing that potential info away by fudging the actual readings in some way.
 


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Offline CW2274

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Re: Wind direction when wind is calm
« Reply #15 on: November 06, 2021, 02:21:07 AM »
When the wind is calm any direction is meaningless, continuing to report the last wind direction is even more meaningless. For previous conditions then use the pastcast conditions based back in time or averaged progressively back over time should be in the reporting loop.
With a good system that is level and has good bearings, it is possible for the vane to move without there being enough wind for the cups to move enough to compute a wind speed.
Also disagree. If you have a vane that moves before the cups spin, then you have a vane that flops around like a fresh fish on the deck or you have cups that engage waaaay too slowly.

Offline Mattk

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Re: Wind direction when wind is calm
« Reply #16 on: November 06, 2021, 03:38:01 AM »
I doubt there is any wind vane anemometer that is perfectly and exactly level which in null wind conditions will generally allow the wind vane to settle and always point to the "Low" side.

This wanting or needing to know what the wind direction was before the wind calmed is a little needless, no wind then there's no direction it's that simple, if one needs a pre-cast then simply look at the archive history. Most are forgetting what ultrasonic's do in null wind which don't have a vane to mislead you, null wind, null speed, null direction.   
« Last Edit: November 06, 2021, 03:51:13 AM by Mattk »

Offline CW2274

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Re: Wind direction when wind is calm
« Reply #17 on: November 06, 2021, 04:44:14 AM »
This wanting or needing to know what the wind direction was before the wind calmed is a little needless
Your myopic opinion is just that.

Offline sky_watcher

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Re: Wind direction when wind is calm
« Reply #18 on: November 06, 2021, 04:58:08 AM »
When the wind is calm any direction is meaningless, continuing to report the last wind direction is even more meaningless. For previous conditions then use the pastcast conditions based back in time or averaged progressively back over time should be in the reporting loop.
With a good system that is level and has good bearings, it is possible for the vane to move without there being enough wind for the cups to move enough to compute a wind speed.
Also disagree. If you have a vane that moves before the cups in, then you have a vane that flops around like a fresh fish on the deck or you have cups that engage waaaay too slowly.
No problem with you disagreeing with what I didn't say.
“The more a man knows, the more willing he is to learn. The less a man knows, the more positive he is that he knows everything...” ― Robert G. Ingersoll

Offline CW2274

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Re: Wind direction when wind is calm
« Reply #19 on: November 06, 2021, 05:21:58 AM »
When the wind is calm any direction is meaningless, continuing to report the last wind direction is even more meaningless. For previous conditions then use the pastcast conditions based back in time or averaged progressively back over time should be in the reporting loop.
With a good system that is level and has good bearings, it is possible for the vane to move without there being enough wind for the cups to move enough to compute a wind speed.
Also disagree. If you have a vane that moves before the cups in, then you have a vane that flops around like a fresh fish on the deck or you have cups that engage waaaay too slowly.
No problem with you disagreeing with what I didn't say.
What ever that means.  :roll:

Offline Mattk

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Re: Wind direction when wind is calm
« Reply #20 on: November 06, 2021, 05:48:02 AM »
This wanting or needing to know what the wind direction was before the wind calmed is a little needless
Your myopic opinion is just that.

Facts may be a little daunting, but never the less facts are facts. Like what is the purpose of knowing what direction was when the wind calmed? It is about as irrelevant of knowing how long ago it was when the wind nulled, could be 5 minutes, could be 5 hours could be any dam thing, something totally unknown, like what is the relevance?

Null wind speed has null wind direction and that's what the system should show in next to real time   

Offline sky_watcher

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Re: Wind direction when wind is calm
« Reply #21 on: November 06, 2021, 05:52:16 AM »
When the wind is calm any direction is meaningless, continuing to report the last wind direction is even more meaningless. For previous conditions then use the pastcast conditions based back in time or averaged progressively back over time should be in the reporting loop.
With a good system that is level and has good bearings, it is possible for the vane to move without there being enough wind for the cups to move enough to compute a wind speed.
Also disagree. If you have a vane that moves before the cups in, then you have a vane that flops around like a fresh fish on the deck or you have cups that engage waaaay too slowly.
No problem with you disagreeing with what I didn't say.
What ever that means.  :roll:
What it means is that I spoke about the cups moving enough to make a measurement. Mattk responded about the van moving before the cups or the cups engaging "waaay to slowly". Why is that different to what I was saying?

The normal microswitch anemometer in many home weather stations must do over 1 to 2 revs to get to get at least 2 pulses to measure instantaneous wind speed, but what normally happens is that the measurement device waits a fair bit longer to estimate the wind speed by counting pulses over a time period. A few use both methods, I believe. Often the weather station then only reports the wind speed every 10 to 60 seconds.
 
So, when I was talking about a wind vane moving before a wind calculation can be done, it is in the context of what comes out of the weather station because that is what is the reading we see. It is not about whether the cups spins a bit when the vane moves and stops.

Hopefully that explains my comment

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Offline fkapp

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Re: Wind direction when wind is calm
« Reply #22 on: November 06, 2021, 06:40:02 AM »
Just brining my question back up here in case got lost in the discussion.

After was mentioned in Cumulus MX is possible to override the calm wind is 0 degrees direction, and report last known direction.

need guidance please where to make this change as have been reading but cant find where to make the change?

Thanks
Frank

 

Offline the beteljuice

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Re: Wind direction when wind is calm
« Reply #23 on: November 06, 2021, 07:04:45 AM »
Imagine what you will KNOW tomorrow !

Offline fkapp

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Re: Wind direction when wind is calm
« Reply #24 on: November 06, 2021, 08:03:19 AM »
Does this report 0 degrees or last direction with speed when checked and wind is calm?
Thanks

 

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