Author Topic: Wind speed at night  (Read 526 times)

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Offline PaulMy

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Wind speed at night
« on: March 01, 2018, 01:58:50 PM »
My Davis VP2 often reports 0 wind during night time.  I daily check and manually report high wind gust in past 24 hours.  This morning I noticed 0 wind in previous 24 hours to about 2:00 am and then ok.  Looked at Weatherlink (now that I have VVP working) and Cumulus and the logs show no wind from Tuesday about 6:00 pm to Thursday 2:00 am.  Wind Speed 0.0, Wind Dir ---, Wind Run 0.00, Hi Speed 0.0, Hi Dir ---.  However there does appear to be wind speed in the WL graphs.  It hasn't been windy the last couple days but expect there would have been some wind during daytime.  Now normal wind speed and gusts since 2:00 am today.  Attached is WL graph that shows the high wind and that shows wind during that time when the logs are all nil.  All other data seems good.  Any thoughts?

Thanks,
Paul

Offline ocala

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Re: Wind speed at night
« Reply #1 on: March 01, 2018, 08:02:13 PM »
Not quite like yours but similar.
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Offline miraculon

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Re: Wind speed at night
« Reply #2 on: March 02, 2018, 09:06:36 AM »
Have you checked your bearings in the anemometer? It might have developed some friction and more wind is required to overcome the friction.

How old is the VP2?

My VP2 isn't nearly as sensitive as my RM Young, but it looks like it takes quite a bit more wind to get yours to spin up.

Greg H.




Blitzortung Stations #706 and #1682
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Offline PaulMy

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Re: Wind speed at night
« Reply #3 on: March 02, 2018, 10:03:29 AM »
Hi and thanks for reply.
The VP2 was installed in 2008 and I have not done anything, maintenance, etc. in any way other than replaced the ISS battery around 2010 and this past fall.  Once this quick blizzard of yesterday clears up I will have to go and check it and see what I can tell on the bearing.  I presume this does not show the sign for a reed switch issue?

That period of zero wind for about 32 hours must have been an isolated occurrence as never had it before and has been fine since.  I though may be something got caught in it, but both speed and direction as 0? and couldn't have been frozen as temperature did get to the low teens.  The shorter (a few hours during the night) of no wind that happens quite often I think are valid.

Thanks,
Paul

Offline Glendower

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Re: Wind speed at night
« Reply #4 on: March 03, 2018, 02:17:06 PM »
I too noticed this a few years ago and did a bit of research on the Internet and this is a good explanation of the condition.

http://wxguys.ssec.wisc.edu/2013/11/18/why-does-the-wind-diminish-after-sunset/

Offline gm85

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Re: Wind speed at night
« Reply #5 on: March 18, 2018, 02:38:42 PM »
I live about 8km away from Komoka and took a look to see how my wind speeds compared.

I went back Sept 24 2017 and switched to the 3-day span (as Weatherlink changed to a Daily Value for High Wind Speed when set to a week span).

I saw the exact same results as you, which explains what Glendower mentioned, that the wind tends to lessen overnight.

Offline miraculon

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Re: Wind speed at night
« Reply #6 on: March 18, 2018, 04:27:51 PM »
I am a little confused here on what the actual problem is here.

  • Is there actually "no wind" (can't feel air movement with the finger in the wind, no trees moving, etc.)?
  • Is the anemometer not turning when there is wind present (what should be enough to turn the cups)?
  • The anemometer is turning, but there is no indication on the display or WL?

Greg H.




Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline PaulMy

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Re: Wind speed at night
« Reply #7 on: March 18, 2018, 04:44:16 PM »
The reason of my original post was that there was no wind recorded for over a day which I am pretty sure is not correct.  The periodic night time periods of zero wind is likely correct as it would be calm for some parts of the night (I was not saying there was no wind whatsoever for the whole nighttime, just significant periods during the night)   I didn't realize it until a day later so did not go and check it out.  I Have not seen the same issue of full 24 hours of no wind since late February, and that was also the first time that I had noticed it.  Whenever I have looked at the anemometer it seems to represent the current wind condition.

Paul

Offline miraculon

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Re: Wind speed at night
« Reply #8 on: March 18, 2018, 04:51:19 PM »
Thanks for the clarification.

Greg H.




Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF