On Fri, 31 Oct 2014 11:55:23 -0000, Uncle Peter wrote:

"This is a fact. -20C air does not make you cold, .
You might shiver if you were naked, but the
shivering will stop you getting any colder".

To me, it sounds like he's talking absolute bull****
and he should be sent to the funny farm, but is
there an element of truth in what he said?....

Nope. Its certainly possible to be quite active when
naked in -20C air and do fine, but just standing there
naked and shivering wont let you survive for long.

Quite shivering (proper shivering not what most people think of as
shivering) is the bodies attempt at trying to maintain your core
temperature. It might be able to depending on the rate of heat loss
but naked in, even still, -20 C air you won't be able to generate
enough heat and your core temp will drop, you'll stop shivering, you
may even feel quite warm (so much so that people falling into
hypothermia may take their clothes off), then you drift off to
sleep...

Active or not it doesn't matter. Shivering replaces active, it's
the
same thing, your muscles are moving. You also have reduced blood
flow
to the surface (all of you, not just your fingers and toes and
other
sticky out things), and brown fat cells which generate heat
directly
from calories.

Yup, which leads to frostbite on your extremities.

Your body won't allow that if you have a reasonably fit body. I've gone
hillwalking barefoot in the snow. My feet go cold and numb at first,
then eventually they go red and warm up again.

Keep barefoot in that snow for a few hours and see what happens. What
temperature was that snow at? Fresh dry powder snow can be very cold,
think in the terms of -40 C ...

--
Cheers
Dave.