Hi,

Does anyone have an idea of how the birds know where to thermal? Do
they have a vario? Where is it?

How about simple inertia?

They may sense the vertical acceleration. Humans do so too,
but they cannot integrate the information well over time. Varios
fix that fault just like attitude indicators fix the problem of
spatial orientation.

birds propably have evolved to work more exactly in this aspect.

Ciao, MM
--
Marian Aldenhövel, Rosenhain 23, 53123 Bonn.
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http://www.marian-aldenhoevel.de
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