Why is 30 feet offical wind measurement?

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I dont understand why 30 feet is the offical height to measure wind?

The higher up you go, the wonder it is so how does 30 feet give a real indication of wind? Go 50 feet and its higher again, 20 feet its lower?

Would not a real indication of true wind with no obstacles be 5 ro 6 or so feet the more true to wind speed indication?

I cannot see how it why 30 feet is used unless it’s to be above every obstacle possible, but being g higher you get more wind, so how can even 30 feet be a true real indication?

I have mine at 9 feet and to me gives a true wind speed indication than at 30 feet.

Also for a 5 in 1 they always recommend a height of 10 feet as ideal.

Anything higher than 10 feet and weather flow your getting false rain. So it’s a compromise.

Why does weather flow, if offical wind speed is 30 feet,? Then if your 10 feet then be able to calibrate it to tell your weather flow its 30 feet up tell it how high your station is and self calibrates to indicate the same type of wind speeds as though your 30 feet up or your station learns the average wind speeds over time and works out the speeds if your station was 30 feet up?

You already ask for height of sky above ground so surely could not be hard for your station to work out at 30 feet how strong the wind would be and adjust accordingly.

I have found through experimenting with 5.1 stations 10 feet is the optimal height and gives the best all round results apart from wind of you got obstacles. Temps, dew point, humidity and rain are the best compromise at this height and closer to offical temps and rainfalls, etc.

The higher you go the higher the wind is rain is more angled so can see how this as well as false rainfall will through weather flow off.

I find mine accurate at 9 feet so far.

Have had 3 days rain and it’s better than my ambient and vantage vue and raincheck does not work over here in New Zealand as far as I know?

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I have mine at 16 feet and do not get false rain indication… It all depends on what you use and how you mount it.

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The WMO standard is actually 10 meters (32.8 feet) IIRC, and I believe that it also includes standards for horizontal distances to potential obstructions that would not be feasible for many home PWS sitings in residential neighborhoods. Is there even an accepted/published standard for adjusting anemometer readings based on anemometer height differences from the standard?

Since you are not running an official weather station, put it wherever it works best for you. I can only get 20 feet on my current mast, and use a second Sky closer to the ground for rain data…

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Can you any number of sky or air through the same weather flow hub?

My Davis vue was happy at 14 feet without tripping any false rain, but took down my Davis in favor of the sky. At 14 feet felt had to many false rain with winds over 28kph, so found the magic number for me at 9-10 feet.

Where I am have not a totally ideal situation but it means compromising. Is close to the house at one point but 3/4 is basically obstacle free, so a sacrifice I had to make.

Think the roof where many have them is not at all the best place as I keep reading 10 feet is the magic number for home 5 in 1 stations and find this basically correct for giving overall best place for best temps, rain, dew points, etc and we dont live 30 feet in the air so think for a home station is rediculous and rain and everything else wont be correct as 5 in 1 stations are not made to be placed 30 feet in the air.

But think a station like the ambient atlas has solved this by allowing a wind extention.

I think weather flow could have solved a lot of their issues by having the rain sensor sperate from the wind.

But yes a sperate sky unit lower down is a great option but weather flow should have had the rain sensor as a sperate item and of part of the wind sensor.

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I hope weather flow sees the sense in a sperate rain sensor and an option to disable the rain sensor in the sky unit if they made a separate rain sensor. Should not have to buy a second sky unit to place lower down?

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I’d also be very happy with a separate rain sensor. I have the Sky at ~25ft and it triggers the rain at 30+ mph. The pole is fixed with wires, etc.

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Yes. I have three Sky and three Air units on one Hub, and WF has even more at their test facility. The Hub firmware and web API’s were designed from day one to support multiple sensors of each type, and my WF UDP driver for WeeWX uses the sensor_map function to support as many different sensors as you want and assign them to different WeeWX LOOP/archive database fields based on your preference.

I’m sure that there is a limit to the number of sensors that can be connected to one Hub, but most of us could never afford to ever reach that limit financially. I’m not so sure about @GaryFunk, though… :wink:

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So this means one could have another Sky (at floor level) and store only its rain data? That’s tempting but not so cheap, though.

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Give http://www.nws.noaa.gov/directives/sym/pd01013002curr.pdf a read if you want standard-ese.

Basically they had to pick something commonly doable that got good enough consistency in reporting.

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Yup:

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smartweather.weatherflow.com/share/910/grid

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The Hub will handle 20 devices.

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Hi Dennisrogersx,

You raise an excellent question. For government, science, aviation and other commercial grade operations the standard wind measurement height is 10m with a flat grassy fetch (land cover upstream of the sensor). As you elude to, most home weather station owners want to know what is happening in the environment where they live… in their backyard. So, we agree, put the sensor where you live… in your backyard, and it will deliver your backyard weather conditions!

-Marty

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Yeah on a house roof or higher it’s not giving the true wind speed in your environment or back yard.

Your temps, rainfall, humidity and dew point wont be accurate.

I know for a 5 in 1 manufacturers say 10 feet as this is the best compromise and gives the best balanced readings and have found this to be true myself.

So having your 5 in 1 or even thr sky unit on your roof is not giving you realistic conditions in your yard at all.

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My preference is to have wind data that tells me accurate wind direction
and speed even in a residential neighborhood. That means 40 ft to get it
above roof peaks. Screen shots are friends Sky about 5 miles from me
mounted at 6 ft in back yard, and my Sky mounted on chimney at about
40 ft.

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You may well get more accurate wind data but everything else will not be correct. Depends on what you want to record accurately. At 10 or so feet your wind maybe more a reflection of what the wind is in your own backyard but everything else will be more correct.

For me would rather have more balanced results.

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Remember that the WF unit isn’t a single sensor set so one can get humidity, temp, pressure at one height/location and wind, rain, and solar radiation in another. You can even do what some of us are doing and have more than one SKY to mount in different locations. I have one 8 feet above the peek of my roof and the other 4 feet above my yard right next to a CoCoRaHS gauge. My station is 5075.

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