Wind speed reckoner

Mossypaw

Well-Known Member
Hold a piece of grass at shoulder height and release it, point to where it lands, take the angle between your body and arm and divide by four, this gives you the approximate wind speed in mph.

Anyone know or use this method ?
 

Mossypaw

Well-Known Member
Kestrel 4000 - ££££££, piece of grass - free.
Kestrel 4000 - needs batteries, piece of grass - doesn't.
Kestrel 4000 - needs taken with you, piece of grass - doesn't.
 

Wrens Mews

Well-Known Member
Kestrel 4000 - ££££££, piece of grass - free.
Kestrel 4000 - needs batteries, piece of grass - doesn't.
Kestrel 4000 - needs taken with you, piece of grass - doesn't.
If you want to guess then grass is fine, if you want accurate first round hits then Kestrel it is.
 

bruce w

Well-Known Member
when the wind moderates i will give it a try thats if i can find some grass most was blasted of a day or so back with a 100 plus mph spell ,shipping containers travel a distance once they get tipped so its along the same line there must be a way of working that out.
 

basil

Distinguished Member
Hold a piece of grass at shoulder height and release it, point to where it lands, take the angle between your body and arm and divide by four, this gives you the approximate wind speed in mph.

Anyone know or use this method ?
How heavy should the blade of grass be to get precise results??
 

Taff

Well-Known Member
I use the hat system
hat needs to be removed- no wind
hat resting on head -2to5 mph
hat placed firmly on head 5to10 mph
hat placed firmly head slightly tilted 15 to 20 mph
hat peak starting to flap chin on chest 25 to 30mph
hat in next field to windy to shoot
 

Outback

Well-Known Member
Years ago a firm I worked for put a crane up to Shetland to work , I finished up working in Nicolson plant hire yard due to the lack of gear and the weather .
The housing schem out the back had the sheds ratchet strapped down and containers were chained down in open areas .

How ever one day we put the jib up to see how hard the wind was blowing and it was 90mph gust's the same day they towed a helicopter out of a hanger at the terminal and the wind blew it over .
 

Alantoo

Well-Known Member
Hold a piece of grass at shoulder height and release it, point to where it lands, take the angle between your body and arm and divide by four, this gives you the approximate wind speed in mph.

Anyone know or use this method ?
Something slightly adrift with the mathematics…maximum wind measurable is only 22.5mph with arm pointing at 90˚ presumably with the grass remaining airborne indefinitely. Anything over 10mph (arm at 40˚) is going to be quite difficult to gauge. Having to learn to accurately assess angle of arm without a protractor, or divide by four without a calculator, lumme!….and knowing how much the turbulence caused by your body would affect the grass' flight...do you let it go actually at the shoulder or at arms length; at right angles to the wind's direction or downwind or was that not specified?

I think I would rather continue to just look at the vegetation around the prospective bullet path. At least that considers topological variations, even an anemometer (or the wonderfully super "hat system"**) can only give you the speed and direction at the point where it is taking the reading.

Alan

** Obviously the relative surface area and rigidity of brim or peak , the current and original fit, the shrinkage caused by weather and age and the date of the reading relative to annual hair cut would have quite a bearing on the precision of the "hat system"…it would need regular calibration against a Kestrel 4000 (whatever that is)…but that goes without saying….
 

Taff

Well-Known Member
I do have a calbration system in place, my hair is cut to grade 5 at the same barber on a regular basis, this will depend on the ambient air tempture, which offsets the shrinkage, I.e. More shrinkage in hot weather, offset by the need for shorter hair. We had problems with the brim flexing too much so reducing the lift-ability and so giving a false reading, this was solved by allowing a build up of dirt while holding the peak to use the cap as a object to make the cows move faster.
As to the ability of the kestrel 4000, I have been known to use the kestrel 1, if it fails to hover a in stationary position it is windy.
 

AN DU RU FOX

Well-Known Member
if the flag on the conservative headquarters flag pole in knutsford is moving,,,,its windy,,,,or its all the hot air rising thats making it flutter!!,
 

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