I work out in the cold, and while it does appear he's wearing virtually nothing compared to what we usually wear in the present day, the quality of clothing pla

I work out in the cold, and while it does appear he's wearing virtually nothing compared to what we usually wear in the present day, the quality of clothing plays a big factor. I've sweated my ass off (literally dripping) at -15C with just a fleece sweatshirt on over a thin tshirt (literally less than 1/5th of an inch of material), but the slightest wind with that on draws all the protection from the cold away. Leathers provide a virtually impenetrable protection against wind, and a real fur below that would have provided great protection against cold. However I found that a simple summer wind breaker over the fleece sweatshirt was enough to get around in the winter <30 minutes outside without getting cold. During my actual work periods (IE 8 hours) I typically go on the heavy side of clothing and with the heavy exercise I do I actually feel at risk of heatstroke at -10C. Considering these guys frequently had done military service, and often were actively in military service, they probably wore little clothing during travel for the same reason that they had to not only regulate heat loss but heat gain to form a balance between being freezing and boiling. It's also worth noting that these expeditions were frequently performed during December, which is incidentally the height of summer in the southern hemisphere. Summer temperatures are between -15C and -35C, which is considerably more manageable than the winter temperatures of -40C to -70C. Note the freezing point of CO2 is -78C (not that at its pressure it would ever freeze in nature).