Measuring Wind (Was: Re: Wind Meters)

Measuring Wind (Was: Re: Wind Meters)

Post by David Sans » Sat, 11 Sep 1993 18:25:15


> I have to differ from your statement here.  The ground wind is great for the
> stunters, but there have been many times when launching a single line kite
> that the kite will hit dead layers -- no wind!!!  It's happened to me many times
> since I have gotten more into the single line kites.

> If you would have said this to me last year at this time, I wouldn't have
> written this, but through my experience this year, you can definitely run into
> less wind at higher altitudes.

well, if i may waffle a bit...

what you've encounted here is "wind shear" which is a change in wind strength
or direction over height.  This sort of change can be quite dramatic,
like 180 degrees or 10+ kts.  There is usually a bit of a change in the
wind near the ground from turbulance, which is why forecast and reported
winds are for the "10m winds", ie measured 10m above ground level.  However
big features many miles away can effect wind patterns (eg "mountain waves").

Wind shear can be very strong and has been attributed as the cause of several
aircraft crashes, including airliners !



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