"Andrew Sarangan" wrote in message
om...
"Mike Rapoport" wrote in message
thlink.net...
"Andrew Sarangan" wrote in message
om...
(Kirk Stant) wrote in message
. com...
"K.P. Termaat" wrote in message
...
My experience is that it works, especially on days with very low
humidity,
but no boomers and only low.


"Mike Rapoport" schreef in bericht
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You will find less lift over water of any kind, even if it is
contained in
vegetation. The best lift is always over the highest, dryest,
darkest
surface around. The water vapor idea is...well...it is hard to
find
a
place
to start...but it won't work

Mike
MU-2


Have to disagree with you, Mike - out here in Arizona, in the desert
areas that are not irrigated, we often find good lift directly over
small cattle "tanks" - small shallow ponds that are scattered
around.
A lot of us have noticed this and compared notes, and it works; if
too
low to get to high, dark ground, I'll head for the nearest pond and
it
will usually turn up a nice thermal. We think it may be due to the
fact that the ponds are in a natural low spot, and coupled with the
little bit of moisture, could be the necessary trigger for a
thermal.

Now obviously, large irrigated farm fields or river basins are death
to thermals - but a local lake (reservoir) seems to have little
effect
on thermal activity - could it be all the drunk boaters?

What's the old saying about never saying never?

Kirk
LS6-b


The adiabatic rate of moist air is about 1.5C/1000ft. For dry air it
is 3C/1000ft. Therefore, assuming that the water temperature is the
same as the surrounding ground (which would be true if the water is
shallow), I could see how one will experience greater lift above
water.

Not for unsaturated air it isn't. The moist rate only applies to
saturated
air (ie in clouds)

Mike
MU-2


OK, 1.5C/1000ft applies only to 100% RH air. But a 50% RH air must
still have a lower lapse rate than dry air, no?

No. The reason that saturated air lapses at a slower rate is that latent
energy is being released as the water vapor changes to liquid, that is the
only reason.

Mike
MU-2