In article ,
ess says...

Not so at the instant the airmass is entered.
After some time - about 0.75 to 2.5 seconds the glider will be close
enough to equilibrium in the new airmass.

Indeed.

I misstated what I meant to say: that the instantaneous position is
that the glider has its original velocity vector but is now in rising
air, so has a reduced AOA until its in equilibrium with the rising
air.

Rising air comes from beneath the wing, and increases the AOA. The
increased AOA produces an increased lift, so the glider accelerates
upward. If the AOA decreased, the glider would begin to sink, and we
know that is not the case in rising air!
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Eric Greenwell
Richland, WA (USA)