This thread reminds me of the original explanation for malaria "bad
air". Everyone knew that he disease came from bad air wafting up
from
hot swamps. It took some actual research to determine that it came
from
a mosquito borne parasite.
Clearly there are lots of arm-chair (desk-chair?) explanations for
why
IAS increases upon entering a thermal, but nobody *really* knows
because
no experimentation has been done to figure it out. Some wise old
sages
out there are certain of their explanation, and maybe they're right,
or
maybe it's just bad air.
This seems like it would be a good youth-in-soaring sort of question
to
solve with real science.

Shawn

This ain't rocket science it is basic aerodynamics. Experimentation
is worthless without a basic understanding of aerodynamic force. You
will only propagate the narrow minded misinformation found in some real
science books. Its takes life long conspiracy to get pilots (private
and commercial) so ignorant about aerodynamic force that they do not
know the simple single difference between the definition of lift and
drag. You have to start when they are young and gullible and hope they
do not practice much original thought or apply what you tell them with
actual occurrence.

When you introduce them to one of the many different inaccurate
definitions like drag is a resistance force hope they do not realize
that the major use of lift in aeronautics is to resist gravity. When
you talk about the dynamics of a balloon preoccupy them with the
aerostatic lift that it produces and do not mention the fact that it
has circumnavigated the earth using drag exclusively for horizontal
acceleration. When you tell them that lift is the aerodynamic force
that supports the weight of an airplane in flight hope that they
don't realize that if drag opposes motion and if that motion is
downward drag is in an upward direction. Explain terminal velocity of
a dropped object on another day maybe they won't put two and two
together.

Why if you were to try something novel like telling them the truth the
hole truth and nothing but the truth so help you god maybe when they
are thinking about an aerodynamic force that impedes the forward motion
or an aircraft they will have an open mind and not just jump to the
inaccurate conclusion that it is always drag. When they are thinking
about an aerodynamic force that accelerates a glider upward they will
not jump to the inaccurate conclusion that it is always lift especially
since the glider is in lift.

It is impossible for the air speed of a glider in normal flight to not
be increased by a sudden thermal. The only way that the glider will not
be affected is if it had no inertia. If the glider moved readily with
the thermal there would be no increase in motion of the glider in
relation with the upward airflow. If experimentation is needed to
figure this out how are you going to be able to figure out the
experiment?

I hate to brag but I am a walking talking aerodynamic experiment. Why
even in my sleep I possess the ingredients for aerodynamic force. I am
a solid object that is influenced by a relative airflow 24-7 as a
result of respiration among other things. Not to mention other fluid
flows like blood and urine. And I have been known to emit a little
swamp gas (what you refer to as "bad air"). To the people that I am
related to this is referred to as relative wind.