Staying warm at Cool School
EIELSON AIR FORCE BASE—The last time I was in this building, the year was 1982, I was wearing an airman’s uniform, and a doctor was looking at the blackened tip of my frostbitten left pinkie. It seems fitting to return to the former base clinic building, about 30 miles south of Fairbanks, for “Cool School,” the Air Force’s Arctic Survival Training School.
The commander of the school, Maj. Guyan Mandich, invited me to take the weeklong course along with a few dozen Air Force men and women. The school runs from October to March, and hundreds of military aviators graduate from Cool School each year.
Looking back on two days of classroom training and three in the woods, almost everything the instructors taught was something I didn’t know, especially when we spent Wednesday through Friday in the hills behind the base. During the outdoor portion of the course instructors gave us a can of pork and beans and two MREs (Meals, Ready to Eat). Those limited rations left us hungry for more than just knowledge by the second day.
We experienced a lot out there, but since this is a science column, I’ll focus on a physical element I found fascinating—the insulating properties of snow and how we used it to trap warmth.
During a classroom session, Staff Sgt. Sean Hanson said that we could keep water from freezing on a sub-freezing night without putting our water bottles in our sleeping bags.
“You can build a snow refrigerator to keep your water liquid,” he said. “I just tried it on a 10-below night, and when I woke up in the morning my water bladder had slush in it, but I could still drink it.”
I had to see that one to believe it, so a senior airman and I heaped snow into a pile about three feet high, waited a few hours for it to set up, and hollowed out a chamber. We set our water bladders together neck down, and covered them with two feet of loose snow.
The temperature didn’t get warmer than 10 degrees F that night. In the morning, we dug our containers from the snow. They were cold, but still liquid.
Our final night in the field, Senior Airman Jason Clapper taught us how to make a “thermal A-frame shelter.” I had stayed in snow caves—sleeping chambers dug out of packed snow—but I had never tried a thermal shelter. To make a thermal shelter, you dig through snow all the way to the ground surface and scrape it bare. Then you build a framework of logs above the spot, cover the logs with a parachute or tarp, and then heap at least eight inches of snow on the entire structure.
“This way you use the heat of the ground along with the insulation of the snow,” Clapper said. “Your shelter should stay about 18-to-22 degrees no matter how cold it is outside.”
I had a way to check that. While building my shelter, I installed a few temperature probes UAF ecologist Knut Kielland loaned me. Every 20 minutes, the probes measured the temperature of the outside air and the inside air. Here’s what they showed:
Even before I crawled in, the temperature inside was 20 degrees, five degrees warmer than the outside air. When I squeezed into the shelter at 9 p.m. and pulled the door plug in behind me, the temperature inside jumped to 36 while it remained 12 degrees outside. After I settled into my sleeping bag, the shelter temperature stabilized at 29 degrees and remained there all night, even while the temperature outside dropped to minus 1. During a good night’s sleep in the cozy, quiet structure, I became a fan of the thermal A-frame shelter.
And, after a week of useful tidbits from the instructors and listening to my classmates’ campfire stories from all corners of the globe, I can think of one word to describe Eielson’s Arctic Survival Training School: Cool.
