Peeling Back Layers: Reconstructing effective use of cold-weather apparel

I think of it as "The 'L' Word," because when people hear "Layering," they tend to zone out. It's a term that carries with it an almost dismissive familiarity, but even avid outdoor enthusiasts frequently have an incomplete understanding of the concept. It isn't really about staying warm. It's about staying cool. It's about temperature regulation.

Layering is about keeping your cool, NOT about getting you warm.

The easiest way to be warm is to grab the biggest, poofiest hooded down parka you can find. If you're doing much more than belaying an ice climber or standing at a bus stop, though, it's easy to overheat... and although being too warm might sound great, your body doesn't see it that way. The "You" of your heart and mind might cherish excess warmth, but your body has one mission: Keep it neutral. If you're too hot, your body will work to cool you down. 

It might strike you as cruel, but it is eminently usual. If we give this particular rabbit hole more consideration, it's quickly apparent that your situation can only snowball until you're totally jammed. To wit, you're overheating so your body starts cooling you down... so you bundle up more, and your body redoubles its efforts to cool you... so you put on an extra hat and do some jumping jacks, and your body works even harder to cool you... all in all, it's not a scenario that ends in comfort, which is why I stress the importance of staying on the cool side of comfort.

Be proactive in removing layers... Take them off before you're too hot. There's a sensory sweet spot in that area between feeling cold and feeling that you'll be warm soon; when you sense you've started warming, or that you're not cold, it's probably time to shed a layer.  The more aerobic your activity level, the more proactive you need to be in removing layers. You don't need to wear much when your metabolism is cranked to high! 

Imagine that you're in your house and the thermostat is on whatever "regular" is for you, maybe 68*F. You're comfortable, maybe wearing a long-sleeved shirt or even a flannel. Now imagine that the thermostat's set at 80 and the furnace is humming along... if you're like me, you won't be wearing much more than underwear. Or maybe you visit someone who you know habitually has their heat set high, so you wear a bit less clothing there than you would at home. Just as these indoor situations are a microclimate of sorts, your body maintains its own microclimate. 

Your body doesn't really care what the weather is like outside. Or inside, for that matter. Your body just wants to be the same temperature, all the time.

By way of example, I've had a sedentary day. I was wearing a very thin merino wool henley and an unbuttoned flannel at the desk; my dog started bringing me bits and pieces of laundry, which means he's bored and it's time to go for a walk. I keep the house around 65F, and it's a bit below freezing outside, around 28F. I tossed on a fleece vest (okay, wool, but same idea), an uninsulated rain jacket, and a hat on our way outdoors. I wore a pair of leather work gloves that were stashed in the jacket pocket and we walked about a mile. When we got home I removed all but the thin merino shirt, since the walk had boosted my metabolic heat production & I was too warm in the flannel. The point is that I didn't need to add much of anything to go outside, because I knew that the activity would turn on my "furnace." 

If I had gone out to sit on a log for a few hours instead of walking, I would've needed to dress differently. Adding layers does add insulation, but if you're headed out to hunt from a tree stand, for example, wearing enough layers to stay warm can restrict your mobility. For sedentary activity you're probably better served by just throwing on one or two big thick layers... 

I know, sometimes it's hard to feel motivated about going out into the cold. Sometimes we don't care if wearing a really warm jacket will make us too warm... if we're going outside, darnit, we're gonna be warm. When it's bitter cold and I'm headed out snowshoeing, and I want to make sure I'm warm enough, I'll toss on a sort of "ceremonial" down jacket or something. I know I won't be able to wear it long. But it gets me out the door feeling cozy, and after moving 5 or 10 minutes I shuck the jacket and stash it. Actually, for single-digit snowshoeing my "go-to" combo is a wool baselayer, a super light windbreaker, a down vest, and a hat. The down vest never stays on long, but it's sure nice to have!

There's a lot more we could discuss, but I wanted to get this idea out there for you as winter comes on. I've met countless people who have approached "layering" as "wearing a bunch of layers to stay super warm," and thought this angle of the concept might be of help.

Comfort In The Cold: An Overview

Let's kick this off with a little role-playing game: You... are not you. "You" have never traveled outside the tropical rain forest you know only as "home." There's no electricity in your village, the outside world is a sort of bizarre fleeting concept... and then one day a stranger shows up. An anthropology grad student. And you fall madly in love. When they ask you to leave with them, you can't suppress your exuberance when you say "Yes!" And this new love of yours gets a quizzical dancing look in the eyes, and says they'll show you a place where boiling water freezes in mid-air... a far, far away land called "Northern Minnesota," where the world is white many months of the year.

You get to Minnesota as summer is drawing to a close, and people warmly welcome you with you tips about how to dress in winter... and you inwardly smile a bit smugly, because you're wearing the sweater that a friend used to wear in the mountains. In fact, you're thinking about taking the sweater off right now, and it doesn't seem likely that temperatures could change THAT dramatically. But as the weeks start going by it gets COLD! And your new friends smile, and say something about the leaves all still being on the trees... and you start to listen to all their snippets of advice. Before long you feel almost dizzy with all these ideas on how to dress for "winter," and although you think there must just be some connection you're missing, a bunch of those ideas seem to contradict each other. What should you do?!

Let's start with a look at physiological need... completely aside from your comfort and not wanting to feel cold, why does your body need to stay warm? What is it trying to do? Why do some areas seem to get colder than others or, conversely, some parts seem sweaty while others seem almost numb from cold? Why does it seem like lots of clothing doesn't seem to make much difference on some parts of your body, but worn elsewhere even something thin can make you feel much warmer? In a word: survival.

As rude and cold and calculating as it might seem, your body is quite aware that some parts of it aren't critical for survival. Conversely, if other parts of your body shut down you'll die... so your body is "wired" to sacrifice some parts of itself to save other parts. Long before you actually get to the ragged edge of survival, though, your body lavishes attention on its critical parts: your brain, heart, & organs. The thing is, your body can only produce a finite amount of heat... like a small furnace in a big house, when things get really cold you have to close off some rooms. If your body senses that critical areas are getting cold, it shunts heat away from your extremities and brings it to your core. That's why our toes & fingers can so often feel cold when we otherwise feel comfortable. 

Imagine, if you would, a house with well-insulated walls... and no insulation in the ceiling or roof. That'd be nuts, right? (It's pretty common for houses in northern latitudes to have two or three times more insulation overhead than in the walls.) Consider that analogy as it relates to winter apparel: If you're wearing a big poofy down parka, it wouldn't make sense to not also insulate your head. You would lose a wildly disproportionate amount of heat through your head.

Let's use a cooking example along a similar vein: You're broiling some steaks and smoke billows from your oven. The smoke alarm pierces your ears. You get out a fan... and close all the doors and windows? No, of course not. The smoke couldn't go anywhere. You open the windows and doors... you REMOVE THE BARRIERS to airflow. You put as little between the outdoors and your smoke-filled kitchen as you can, because doing so will get rid of all that air that would otherwise linger in your kitchen for days.

The point is that "creating" warmth really means RETAINING warmth. Your body produces heat; it's your job to keep that heat near your body, which we accomplish by creating DEAD AIR SPACE. Great insulation is sort of a nightmare-ish labyrinth for gleefully excited warm air. We make it more difficult for warm air to escape the microclimate over our skin. If you insulate some parts of your body and not others, the parts that are not insulated will, obviously, lose a lot more heat... which is why you can be wearing a big down coat and be cold, but add a hat and stay warm. By extension, if you wear a super-thick, wind-resistant jacket and counter it with a thin beanie with an open weave... you're obviously not as well insulated on your head, and you will minimize the efficiency of your big down jacket because you're blowing all kinds of extra heat out through your poorly-insulated head.

This is partially where the old saying, "If your feet are cold, put on a hat," comes from. Your head can lose proportionately more heat for its given body surface area, precisely because of mechanisms that shunt blood from your periphery to feed the core... there's more blood flow there, and it's more exposed.

Thermoregulators throughout your body constantly collect data and forward it to your main computer. If your temp is dropping, your peripheral blood vessels will constrict, which will help shunt warm blood to your core. Conversely, if you're overheating, your peripheral vasculature will dilate, maximizing surface area exposure and radiant heat loss. Incidentally, if you're wearing clothes or footwear that constrict or compress, it can have a similar effect of diverting some blood flow away from the periphery and toward your core. And this, this seems like a good place for us to pause. Next time we'll talk about what the whole concept of "layering" really means, when it works best, when not to dress that way, and how to make it work effectively when you do.