I believe you see a parka shell and not a field jacket.
It has been a long time since I was at Ft. Greeley and "blowing up the Alyaska Pipeline"(1976) but the Army is big on layered clothing.
For neg 40 deg weather the unifirm consisted of: T-shirt, long johns, wool shirt, field jacket w/liner and parka shell W liner. There were times when pulling an akio, we were down to T-shirts in spite of the temp. The biggest danger was getting overheated and wet.
New materials such as gortex, and thinsulite were in the developmental stage and I am sure the clothing is lighter and more comfortable. The boots were vapor barrier with a valve to equalize pressure -- an improvement over the original "Mickey Mouse" thermal boots.
Pictures can't really tell the whole story.
Time for another FOG story:
We were to jump into the tundra and make a long overland trek to "blow" the Alyaska pipeline. The aircraft were to be maintained at temperatures below freezing. Instead, the crew had the heaters up to shirt sleeve temp while we were dressed for minus 40 degrees. To make a long story short we got violently ill. I picked up the crew chief's tool tray and puked into it. Served him right. My over whites (a layer I forgot) were then over orange -- the color of the orange juice I had for breakfasr!!
