I fly in the Reno area and I've seen big dust devils
that carry dirt into the air (starting at 4300' MSL,
ground level) up to 12,000' MSL.

At the ground the 'thermal' is rotating but it does
not go up too far (maybe 2000' to 3000' AGL for a real
strong one) before there is no perceptable rotation
of the dirt in the air.

At the average altitudes we fly gliders, particularly
just below clouds (at least 500' below, right?), there
is no special reason to be turning right as opposed
to left (or vice versa) other than your initial best
guess for centering purposes.

JLH
Ventus C

I think the rule for dust devils is, "There ain't no hard rules." I've seen
'pipe stem' dust devils reach over 20,000' in southern New Mexico. I think
there is good evidence that once rotation sets in, it continues at height
but slower than near the surface. I can tell you that turning against the
dust devils rotation at low altitudes works a lot better than the other way.

Bill Daniels

"James Hamilton" > wrote in message
...
> I fly in the Reno area and I've seen big dust devils
> that carry dirt into the air (starting at 4300' MSL,
> ground level) up to 12,000' MSL.
>
> At the ground the 'thermal' is rotating but it does
> not go up too far (maybe 2000' to 3000' AGL for a real
> strong one) before there is no perceptable rotation
> of the dirt in the air.
>
> At the average altitudes we fly gliders, particularly
> just below clouds (at least 500' below, right?), there
> is no special reason to be turning right as opposed
> to left (or vice versa) other than your initial best
> guess for centering purposes.
>
> JLH
> Ventus C
>
>
>

I've never thermaled in a dustdevil, but wouldn't rising particles hurt
the glider over time?

-Nik

I am sure the cheat grass that was hanging off the leading edge of the
wing, after I took a 9000ft climb in less than 4 minutes in one,
certainly hurt the performance of the glider. Fortunatly I missed the
few Garbage bags that were floating around in it as well.

It did raise a few eyebrows as a rolled to a stop on the runway and the
Cheat grass finally fell of the leading edge of the wing on to the
Tarmac.

Brian
HP16T N16VP