Good topic C2,
Great info.
Even though my profile says I am in Florida, I spent some time in cold places.
I am also a former Marine and after that joined the Army.
I retired from the 10th Mountain Division at Ft. Drum in upstate New York, I also was in Colorado and Iceland.( and a few hot sandy places)
Two words I learned very quick - "Cotton Kills"
Stay away from cotton undergarments or t-shirts in cold weather, especially wet cold.
Go with polypro, wool, underarmor cold gear, etc..
I can't add anymore to what C2 said, he nailed it.
Semper Fi, and "airborne"
John