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Old 7th Mar 2008, 20:29
  #393 (permalink)  
PBL
 
Join Date: Sep 2000
Location: Bielefeld, Germany
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Wise words, Avionista.

As to gusts, I think we don't know much about them. There are a bunch of wheatfields around here, and every year as I cycle past, I notice roughly circular areas some 5-10m in diameter *flattened*. Now, that's in normal weather, and I think it would take some 50+kts to break a stalk in the middle of a dense wheat field. There are small, narrow, tornado-like funnels in most normal storms, it seems.

I used to live in an apartment that backed onto a meadow at the end of a long funnel of parks that came down from the hills. The meadow was about 100m wide, and in the middle was a copse of tall conifers, about 20m wide. There was a fair wind storm a few years ago, and after the storm I noticed some areas of flattened grass. The grass stalks were some 1m high at that point. I went to look. On the lee side of the copse was a circle about 2m diameter in which the grass had been completely flattened, in a circular pattern. Everything outside that circle was standing upright. That is, a funnel of unusual strength had grounded exactly there, all 2m of it. 60kt or more, in circular form, and confined to 2m diameter, in a storm of average 30kt or less.

Now, something like that isn't going to disturb an A320, because it is too localised (I once had a dust devil go right over me, and my parked airplane, at the Mammoth Lakes airport in the Sierras. Entertaining, not worrying). But widen it three or four times, as in a serious storm, and you have something that could kip a wing. Or flatten a golfer.

PBL
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