[EMAIL PROTECTED] writes:
>.maybe because their wings allow
>> them to do right turns in a left turning thermal, but "most birds will
>turn
>> counter-clockwise, in the Northern Hemisphere, with the thermal" (a
>quote
>> from a handout that was a page copied from a textbook,
as a teacher of physics, I will tell you that TEXTS are the worst sources
of info. Even the very best in undergraduate and graduate school have
mis-conceptions. (Ironically, the worst misconception is "centrifugal
force" - a fictious force that is unfortunately probably necessary to
comprehend the coriolis effect of LARGE masses of air)
As was mentioned prevously by this author and others - thermals DO NOT
have a definite turn (due mainly to their short life, with such a weak
force (coriolis) it takes time to get the stronger thermodynamic random
movements organized), they are meta stable bubbles of rising warmer/more
moist air that slant (usually) with the prevailing wind or drift randomly.
As the warm bubble rises, the air cools due to lower pressue and
expansion and moves "out away from center" of the way for the underneath
warmer air - which ends up looking more like a rising (no pun intended)
donut of air. Cu's top out this way.
Birds ARE NOT flying counter current in thermals - there will be a local
and temporary direction in a portion of the larger bubble, but not an
organized overall spiral AND definitely not because of the corolis effect.
IMHO
Old timers will remember the "Taft Trash Movers."
jim ealy
AMA Life Member #43
PS if you are going to flame with "WHO the H*** cares???" -save bandwidth
and use reply to sender only.
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