So we’ve had one of the nastiest winters ever. And I’m following the expert’s advice and wearing layers. Clothing upon clothing upon clothing, etc. I even bought some oversized pants to wear over my normal sized pants.
But how many layers before it’s not any more effective? I would think at some point layers become redundant.
It’s not layers alone. The type of layer matters as well. But the question you pose is the same as with any type of insulation. It is, in most terrestrial (and your average celestial) situations, possible to get enough insulation. That’s the point where you retain a similar amount of body heat to a nice shorts-and-tshirt day. If you add more insulation you will overheat.
There’s not single correct answer though. “Cold weather” is not specific enough. And it will even vary from person to person, and depend on their activity level.
It’s more about the quality of the layers than the number of them. At the least you want a lightweight base layer that will keep you dry, an insulating layer to retain warmth, and an outer layer to protect against wind and rain.
Dry insulation is mostly the same no matter what it’s made of. The number of layers isn’t as important as the thickness of the insulation. Big puffy down jackets accomplish all the insulation you need in one layer, but it’s harder to adjust for when it’s not frigid out. A few layers allows you to adjust to the conditions.
People typically talk about a wicking layer next to the skin to transport sweat away from the body, but again that’s an issue only if you’re sweating. It’s much more important when exercising.
A windproof layer on the outside it also critically important, since wind will draw away warm air that the insulation is keeping close to your body.
I do not live in snow country, but I am a frequent visitor during winter months. My usual outfit is no more than 3 layers, and as naita stated, it all depends on how cold we are talking about, and the type of materials in your layers. I will be skiing or snowboarding, so pretty active, and I run warm when active, so while I can be comfortable, someone with less body mass and different layers could be freezing on the same day. Even on stormy days, it’s 3 layers for me upstairs, and 2 below.
I find more than 3 layers starts to restrict movement and squeezes out the warm air from your layers. I always tell people not to “bundle-up” as they usually wrap themselves too tight - air is what insulates, not materials, so the more air you have between your layers the better off you will be. Of course you need to stay dry as well, so a good shell on the outside to keep the wind and wet out is also required.
Well, yes and no. As naita and DCnDC have said already, Quality matters: two cotton-T-Shirts on top of each other may help less than one microfiber undershirt that transports sweat away from your Skin.
Also, the activity Level: if you sit around in a howling snow storm, even the best Anorak won’t Keep you warm through an entire night (that’s why mountaineers on Everest and similar summits carry bivouc bags).
If you know you are taking a light stroll you Need different clothes than if you are doing heavy work - avoid overheating - or if you are sitting still (fishing…).
In one older Action novel (so fiction maybe based on fact?) in Alaska, one old-timer warned the newbie about doing everything slowly at -40 Celsius, because he learned it from the Eskimos: If you worked quickly, you breathed quickly through your mouth = cold air into lungs = get ill and die
also, sweat on your Body = makes you cold = get ill and die
(that was in the 1960s or so, before the Invention of microfiber high-tech underwear).
In another novel, a native Eskimo tells his newbie friend, that if he ever starts to overheat outside, he should never open his Anorak fully - too much heat escapes that way; instead, stand still and just pull off your glove, that allows your Body to cool off slower and gradually.
Today, in Addition to high-tech underwear that transports away sweat; and thin-layer wind-resistant fiber, there are also Gadgets where you have gloves even Anoraks which can be heated with a rechargeable battery (here an example - no ad for the shop intended infactory Beheizbare Handschuhe Gr. M)
So you can today prolong creeping cold from extremities.
Having many layers isn’t so much about extreme conditions, as it is about extreme changes in conditions. If it’s going to be a steady -40 all day, and you’re just going to be standing in one spot that whole day, then you just get something sufficiently thick (no matter how many layers it has) and stick with it. But if you’re going outside before dawn at -40, and by noon it’s -20 and you’re doing heavy activity, then you’re going to want to be less insulated (but still pretty well-insulated) at noon, and if your only option to do so is to take off your four-inch-thick down coat, then you’re pretty well screwed.
Second the good outer shell to stop the wind. It should be fairly stiff.
Except for extremely low temps, I do this (when I need multiple layers for maximum adjustment):
Long-sleeved polypro shirt as a base;
Long-sleeved cotton shirt (usually something simple, like a button-down, so I can strip to it and look nice);
Sleeveless microfiber vest;
Long-sleeved down under-jacket (I use a simple one from REI); and
Mountain Hardwear shell (with a good integral rain hood).
This is plenty warm enough and I can easily remove any or all three outer layers and jam them in a day pack. The shell over just my shirt is not too hot for days in the 50 degree F range and is great for rain.
I could wear a snorkel, a heavier down jacket, or more layers, but I find this gives me the widest range of adjustments, as well as providing protection against all types of precip.
Generally speaking, in outdoor activities you need a maximum of four layers:
[li]A wicking under layer to draw away moisture from the skin[/li][li]An insulating inner layer to retain body heat[/li][li]A protective outer layer to that provides some additional insulation as well as protecting underlayers from damage and offering pockets for gear stowage[/li][li]An waterproof or windproof ‘weather shell’ that blocks rain, wind, and snow from wetting inner layers.[/li][/ol]
Depending on conditions, type of activity, and gear, one or more of these layers may be combined or eliminated (no need for a weather shell in sunny, still conditions), or your wicking and insulation may be combined into a single garment. Alternatively, in really cold conditions you may want two or more insulating layers so that one can be removed during energetic activity or it it gets warmer.
There’s no reason 3 and 4 can’t be the same layer. In fact, I see no reason for #3; all that is part of my outer layer.
I was skiing in -20 F temps recently and I generally went with 5 layers on my upper body; 2 tight under layers, two insulating layers (usually a sweater and a vest), and an outer layer; and 3 layers on my lower body; base layer, insulation, and shell. The key IMO to staying warm in those conditions are what you wear on your head, hands, and feet. Keeping your body warm is relatively easy. Keeping fingers, toes, and face warm is more complex.
The reason to have a separate weather shell that is waterproof is that it can be removed when it is not wet to avoid trapping persperation, or it can be used as an outer layer without insulation in warmer conditions or more in active movements. I’m not pulling this out of thin air; it has been standard layering advice from NOLS and other outdoor activities experts for decades.
I’ve on more than one occasion used five layers, because I don’t own sufficiently insulating clothing to make do with four in particularly cold weather. If my basic wardrobe was even less cold weather appropriate, I’d wear even more. (Given my wardrobe had sufficiently loose items.)
It depends what you are doing and how long you expect to be out in the cold. I’ve worn 5-6 layers to go sit in a hunting stand for 4 hours at a calm 5deg. Without the added wind block layer. I’ve also worn a lined windbreaker over my jeans and T-shirt in windy sleety 5deg to go shopping with the wife. That is based on the belief that I cannot damage my skin or suffer permanently in the minute or two to walk across the parking lots.
All the training I’ve had and materials from most manufacturers use a 3 layer system. Outer waterproof layers are breathable (to varying degrees) and I think the distinction between layers #3 and #4 are relatively meaningless at this point.
But either way will work, it’s more of a refinement than a disagreement.
Whenever people ask about dressing warmly, people always, always mention a wicking layer. But that’s not necessary the vast majority of the time you’re outside in the winter. Are you doing a winter sport? Chopping wood? Shoveling snow? Raking the roof? Then you need a wicking layer. The rest of the time you won’t sweat. At least not outdoors, not even if you take a nice long walk. You will sweat in a store when you realize they’ve turned the heat up way too high for how warmly you’re dressed, but not outside.
Normal cold weather dress when you’re not going to be busting your butt for an extended amount of time is a sweater or other long sleeve top, and a coat. If it’s really cold you add an under shirt, if it’s really, really cold (single digits or colder F), thermal underwear under your sweater and pants. When it’s that cold, inside will be damp/chilly too, so the thermals won’t be overkill.
Being able to move comfortably, and not passing out from overheating when you go back inside are serious considerations on most wintery days. Most people are going to be inside most of the day, so we rely on hats and gloves, and scarves to add warmth when we’re outside, not adding lots of clothing layers.
In my experience it doesn’t matter how cold it is, but how much the wind is blowing (along with what you’re doing).
I’ve been out in well below freezing, but full sunshine and no wind, in a t-shirt, and stone cold sober. I was shoveling snow at the time, but I wasn’t cold. I’ve been out in 45F, wind that would knock down a full grown man, and been freezing my butt off, even with almost all exposed skin covered.
Regarding hands: there are more kinds of gloves than can be counted. In cold windy weather gloves made for skiing are good. Between 0F and -20F snowmobile gloves have worked for me. Colder than -20F requires mittens. I’ve had good luck with double-thick boiled wool mittens covered by water/windproof shells. Those little chemical heater packets are good to have.