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