Some of you may have read this paper by Paul Siple. It's a bit of a classic. Let's see if this link works. You might not have access to it unless your at a university or someplace. I might be able to email the *.pdf if anyone was interested.

http://www.jstor.org/stable/985325?&...ice=showArticle

Here are the contents...

Introduction
The human body as a heat-producing machine
The major source of heat production
Minor causes affecting heat production
How the body releases or conserves its heat
The cooling demand of the atmosphere
Clothing as an insulator of body heat
Practical formulae for computation of clothing insulation
Principles for keeping the body warm
Protection against cooling by moving air
Protection against vaporization
Three methods of dressing
Cold-climate underwear requirements
Outer clothing requirements
Principles for keeping the hands warm
Principles for keeping the feet warm
Principles for keeping the head warm
Summary
Bibliography


It is very readable, and both objective and practical. What I found most interesting was the effects of solar insolation, and the effects of the storage capacity and insulating ability of the outer 1-3cm of skin when in the vasoconstricted state, also the difference betweeen feeling cold and actually being cold. That helps explain in more quantifies terms why we can wear very little walking to the bus stop and even waiting for the bus, even for an hour, but how the cold will eventually catch up to us and overcome us unless we insulate ourselves better and/or produce more heat. Similarly, wool has a great capacity to feel warmer as it slowly absorbs water vapor, but it will eventually needs to be dried out, rather like recharging a thermal battery.

I would like to study more about how wool absorbs moisture, (up to 35% of its bone dry weight without feeling wet), and how quickly and effectively it can be dried out now and then, either by fire, or solar insolation, or body heat, and perhaps dry wind. Also wondering when freeze drying at night might be effective.