Outdoors in the Winter

Mark Verber

The following are rather incomplete notes I have made at one time or another about being in the outdoors in the face of cold, snowy conditions, with a focus on backpacking. It is not as complete as most of my posts about backpacking, though it will likely slowly improve when I stumble across something I don’t want to forget. In my youth I regularly went backpacking in extreme cold weather (e.g. daytime high 0F at best, howling winds, even colder nights). I spent several decades in more temperate winter conditions, e.g. lows between -10F and 20F, days 0-35F. Since 2015 I am doing almost no winter backpacking. My wife doesn’t enjoy it, and while I love solo backpacking through shoulder season, I find solo winter trips no fun.

I would recommend the following books as a good source of information related to winter activities.

Web resources that I found informative

Other books which might be good but I haven’t read them include:

Safety Issues

Winter conditions can be harsh and can be dangerous. The first building blocks for a safe winter outing are basic survival skills, first aid (especially treatment of cold related injuries) and pay close attention to the weather and environmental conditions. There are a few issues which are primarily applicable in the winter.

Snow Blindness & Sun Burns: It is very easy to get a bad sun burn in the winter, especially when engaged in alpine activities. High altitudes means there is less atmosphere to filter out the suns rays. The cold weather keeps your skin cool which means you don’t feel the burn as quickly as you would in hot weather.  Finally the snow will reflect a fair amount of sunlight which means overall glare is worse than it would in snow free environments, and that you can burn skin which overhead shade would normally protect (like the underside of your nose and chin).. Make sure you protect any exposed skin with sun screen.  Wear sun glasses or shaded goggles with >99% UV filtering. Nothing is worse than buring your eyes and experiencing temp snow blindness.  Pretty much kills the trip. Don’t take a chance, wear sunglasses.

Exposure: Often times winter conditions are cold, dry, and windy. The mildest risk is chapped skin. Worse is frostbite and hypothermia. Prevention is the best solution for these issues.  In colder conditions you need to keep your skin covered and pre-heat your air. More about them below.

Avalanche Safety: You need to read the terrain and manage your risk of being caught in an avalanche.  The most danger locations are on north faces on slopes which are between 30-45 degrees. Clean signs of danger of broken or bent trees, concave bowls, gullies, etc.  If you need to cross high risk areas, you should send people across one at a time. Once the first person gets across, they should watch the following folks until everyone gets across. You should know properly self arrest. There is a helmet cam video of a guy going down in an avalanche which is pretty sobering.

Snow Rescue: Equipment (shovel, probe, beacon, avalung) and methodology.

Carbon Monoxide Poisoning: Running stoves in confined spaces can be dangerous, but is sometime necessary. Butane / Propane mixed with side jets produce less carbon monoxide than other stoves.  Read the five part series Stoves, Tents, Carbon Monoxide.

Stay Warm: Understand Thermal Mechanics

You body core needs to maintain a temperature of 98.6 F (plus or minus around 8 degrees). Beyond this narrow range you are in serious danger. [Reference to core temp chart]. A naked human sitting in 32F conditions would be reduced to a state that they couldn’t take care of themselves in less than 20 minutes.  In 32F water this takes less than 1 minute.

Most of the following sections text is just an outline.  For more content, check out BPL’s article about Thermoregulation. Additional insights can be gained by exploring the theory of heat loss and cooling and the behavior animals use to stay warm in the books Life in the Cold by Peter Marchand and Libby Walker and Winter Ecology by James Halfpenny. The book The Hot Brain by Carl Gisolfi discussion development in view of the the need of thermoregulation for the brain to function effectively. If you want to see a clear mathematical models for much of this see the open textbook Body Physics. There is an interesting paper about Thermal Efficiency of a Human Being.

Heat Generation

The two large sources of heat are “excess” heat generated as your metabolize food and heat generated as your muscles perform work. An “average” person’s base metabolism generates around 70 Kcal an hour. Heavy aerobic activity can increase this by nearly an order of magnitude.  If you are getting cold, getting active can really warm you up.  The activity doesn’t even need to involve large movements, simple isomorphic exercises can do the trick and minimize cooling convection that activities like jumping jacks would cause.

Both your basic metabolism and the energy for exercise is coming from the food you eat. To keep your body warm, you need to make sure you are eating enough food and are well hydrated to keep your body’s system working well. While not required, I typically recommend eating hot meals and drinking hot drinks. I think the amount of energy you get from the food’s heat is small compared to the energy packed into the food, but most people find hot food is more appetizing and gives them a psychological boast. It goes without saying that while alcohol might make you feel warmer, your will actually lose heat faster because your capillaries are more relaxed, causing more blood flow near the surface of your skin.  Skip alcohol and enjoy your hot chocolate with extra cream or butter.

You can also use external sources of heat. The sun transfers around 1000watts / square meter via radiation.  So standing in the sun (when it’s available) can do a lot to help you stay warm. Sitting near a fire or stove can be somewhat helpful but care must be taken not to overheat and then start to sweat. I have found chemical heating pads (typically sawdust & iron filings) provide a moderate amount of heat and can be useful. I have been  disappointed with the performance of the reusable, salt based hand warmers because while providing a pleasant warmth, which could be held in my hand, the amount of heat wasn’t enough to really help when I was cold and they lasted less than two hours. There are also solid fuel hand-warmers, and hand-warmers that make use of liquid fuel like the jon-e line.  The liquid fuel seemed to put out more heat. In extreme color this was my favorite type of hand-warmer but with both you need to be careful about carbon monoxide accumulation that they other handwarmers don’t have. The most common external heat source I use on a regular basis are hot water bottles. Boil water in a pot and then pour the water into a water container. I normally don’t use Nalgene water containers. Winter camping is the one exception because most light weight water containers will melt. The lightest container I have found that doesn’t melt are gatoraid bottles… but I don’t normally use them because I don’t know if the plastic is likely to leech chemicals when heated by the boiling water. The best places I have found to use the water bottle is between my legs where it can heat the blood in my femoral arteries which then warms the rest of my body.

The Bodies as a HVAC System

Blood works like a radiator system.  Can be used to cool the core and warm extremities. Note: this means that if you can heat one section of the body (especially where you have a large artery, you can help warm your whole body.  In colder weather the body constricts the blood vessels in extremities to reduce the speed that you lose heat. The one extremity were no constriction happens is your head. This is why wearing a hat and something to protect your neck is extremely important when trying to stay warm.  There is a old saying “You feet are cold?  Put on a hat”. As you can see, there is a lot of truth in that saying.

Radiation

In warm, still conditions, you you lose 50-60% of your heat through radiation.  Radiation is much less of a factor in windy conditions, or in colder weather when you are wearing thick clothing layers. When wearing thick layers of clothing the radiation energy is captured by, and retained in your outer layers.  1-2 inches of material will capture most of your radiated energy.  It is possible to retain a significant portion of your radiated energy through the use of reflective materials such as what is used in emergency blankets.

Conduction

Conduction cooling is when you loose your warmth by touching something. In most cases this is only an issue for your feet and sometimes your hands. You feet will be conducting heat through the soles of your shoes, and you sometimes touch items with your hands.  See the clothing sections about how to protect your hands and feet. In cold winter having a foam pad to stand on can be a great help in staying warm.

Convection

You can think of convection as conductive cooling through the movement of fluids (liquid or air).  You heat up the fluid, and then it moves away, pulling in colder fluids. Water is 24 times more effective at moving heat than air.  This is why getting wet can be so dangerous in cold weather. This means you want to stay dry. If you get wet, your first priority should be to dry off. Convection is also why you want a good seal on the edges of your insulation layer, especially the neck. Otherwise hot air will escape through your neck which pulls color air in at the bottom, creating a chimney effect.

Evaporation/Breathing

In colder weather, <0F, the combination of evaporation from your breath and convection cooling from warming up air on the way to your lungs and they exhaling the air you just warmed can use up almost 1/2 of the energy produced by a basic metabolism. According to one scientific paper, you can lose 1/4 of your heat if engaged in heavy work with rapid breathing. Having a scarf or a 3M air warming mask can be very helpful by pre-warming incoming air and keeping the humidity up.  If I was regularly facing extreme cold I would give a Polarwrap a try, but for now alternate between a PolarBuff, scarf, and 3M warming mask.

Retaining Your Heat

Two of the most important ingredients for staying warm are covered in the next two sections on having the right clothing and making sure that you have adequate shelter.

Stay Dry: Water moves heat 24x more effectively than dry air.

Use sit/standing pads: The ground is cold. If you are standing around, stand on a foam pad to minimize heat lose from the soles of your feet. If you are sitting down, sit on a foam pad.

Make good use of insulators you have: If are are careful not to get it wet, you can use your sleeping bag for more than sleeping. Get into your sleeping bag to warm up. If you are careful you can do many things such as cook from the comfort of your sleeping bag. You can wear your sleeping bag as a shawl or cape. You can wrap yourself in your foam pad.

Stay away from alcohol. Yes, your hands a feet “feel warmer”, but you are interfering with a number of body system which will keep you warm.  Alcohol does significantly more harm than good. Also keep in mind that alcohol doesn’t free a 0F… so if you have alcohol which has been chilling and is below freezing, you could do yourself some real damage by trying to drink it.

At some point I might move specific information about clothing into this page.  For the time being, check out my Outdoor Clothing and consider using vapor barriers. As those pages discuss, avoid sweating / don’t over insulate. Use layers. Not just your torso but also your head and hands. It’s much easier to dry out a glove system which includes a liner, a WP/B shell, and a some sort of insulated mitten with a highly breathable shell.

There are some good hints other places:

Shelter

Western man has come to take shelter for granted. We live in houses, we often travel in cars. We are often unaware of how much protection we derive from these shelters. Even the best clothing system can’t fully protect us from extreme conditions.  There are typically three types of shelters that are used in the back country:

Tents: Do not use double walled tents which have a mesh inner tent. Either use double walled tents which have a solid fabric inner tent or single walled tents to cut down airflow and keep spindrift out of your living area. You want a high vent to let moisture rich air to escape before it condenses on your tent and turns to frost. In many locations winds are much higher in the winter and you need to worry about snow load. This means you want tents that pitch very taut and have steep walls, and have sturdy pole systems. In most cases I would recommend not letting a lot of snow accumulate on your shelter.  This means getting out and shoveling snow. Not the most fun, but you just need to do it.

Tarps: Pyramid, Hex, or Tipi shaped tarps can work well. Some are made to function with small stoves. You can dig out the “floor” for extra room. You should bury the edges to seal out the wind if it doesn’t have a snow skirt. Note that during heavy snows, the snow tends to slide down the slides of pyramids and accumulate which will slowly collapse the edges of your shelter unless you shovel it off.

Snow Structures: It can be significantly warmer in a snow cave or igloo than in a tent.  You should know how to dig a snow cave. There is a book (which I haven’t read) about How to Build an Igloo.

Know how to use snow anchors and other ways to Ditch Your Stakes (Mike Clelland)

I have a few reviews and more information on my Winter Shelters page.

Winter Camping Life

Managing water supply. Pre-form snowballs you can drop into the pot. Hot water bottles at night are morning seed water. Black dromedary bag in sun to conserve fuel. Add snow to bladder inside your jacket if snow is clean for daytime water without boiling.

winter-sleeping-systems-trying-vbl

Going to bed

Camping in snow

how to dry clothing in winter (link broken content not in archive.org) included lots of good tips. some I recall socks over your shoulders when walking, or by your stomach when in your sleeping bag. wrap damp clothing around a sealed hot water bottle

stoves: in many cases you will be melting snow for water. this will take a lot more fuel and you really want a larger pot. butane in canister stoves liquifies at 31F. You can use upright stoves colder than that if you keep the canister warm (like inside your jacket). Now that PowerMax fuel canisters are gone, I generally recommend liquid fuel for extreme cold.

Various Hints

Some of these should be incorporated into the sections above

  • In extreme cold always wear liner gloves. When it gets really cold your skin can “stick” to metal which is very unpleasant. If you are always wearing liner gloves this won’t happen
  • Traveling in deep snow (except when skiing where the ratio between up and down isn’t skewed toward up) will be much slower than “hiking” and takes more energy. Plan accordingly.
  • Big rocks and trees can hold warmth compared to freezing air. In deep snow you will often find yourself postholing more than normal near them.
  • There is a lot less daylight in the winter than summer. You will likely be in your shelter, awake longer than during the summer. You will likely be using artificial light more than summer trips and cold weather affects batteries.
  • Use external battery packs for your lights so the batteries can stay warm under your coat.
  • If you need to go to the bathroom, do it, don’t wait around.  Bring a pee bottle so you don’t have to go far. Mentioned in Going to bed… but it’s worth repeating. Some people recommend pouring out the pee bottle immediately so it won’t get too full and you don’t run the risk of it freezing. When you do dump out your pee bottle be consistent were you dump it some you don’t use that area for snow to be melted into water.
  • Before you go to bed fill a pot with snow and then make a number of snowballs and leave them by the door so getting water in the morning is as easy as possible.
  • Take only freeze dried food. Anything that has any moisture will freeze really solid in extreme cold.
  • Don’t forget that food won’t spoil, so feel free to bring butter, etc which you can melt into your foods.
  • Tent poles can freeze together. You might need to warm them up to separate them. I have normally used the backwash from a stove. Jerry Goller claims that if he gets a mouth full of warm spit putting the pole in his mouth warms it enough to come apart. I am not going to try this until I hear a number of people say this works without freezing their face.
  • Expect snow storms so make sure you know where things are in case a snow storm covers them up. Items like skis, poles, snowshoes should be placed into the snow standing up rather than lying down so they are easier to find.
  • Never wear so much insulation that you feel hot or start to sweat. If you are starting to feel warm ventilate, remove a layer, or drop your activity level. Realize that then engaged in heavy work you need 8x less insulation as when you are asleep, and less than 4x the insulation when you are gently walking around.
  • Know the early signs of hypothermia and be on the lookout. Once you are fully hypothermia you will typically no longer be thinking clearly enough to recognize the signs.
  • If in sub freezing temperatures for extended times, either use a vapor barrier liner or an over-quilt which is sufficiently warm to shift dew point into the quilt, beyond your down sleeping bag.
  • Even when it is below freezing, putting you sleeping bag in the sunlight (protected from the snow underneath) can warm it up enough to release accumulated moisture. It’s good to have the inside black color.
  • Don’t trust that other people’s footprints are a safe trail. I have found people are not great at navigating and just because someone has taken a route doesn’t mean it is a good one. Use your map and compass (or GPS).
  • Put your boots under your pillow or in a sealed in a waterproof bag in your bag to keep them from freezing. This isn’t so much to avoid the discomfort of putting your feet into something cold as much as if your boots freeze solid, it may be nearly impossible to get your feet into them.
  • If you are using vapor barrier socks during the day, make sure your feet get to dry out overnight in your sleeping bag.

Snowshoes

Type of snowshoes…

“Features” or Characteristics

  • Float: How many square inches of surface space your snowshoes have. Powered needs the most float. Ice or hardpack need little or no float.
  • Traction: The harder the snow (or ice), the more you need traction features. Most snowshoes have crampon like teeth under the ball of your foot. Some have teeth under your heel, some turn the whole frame into traction (MSR Lightning).
  • Weight -vs- Float: all things being equal, get the lightest snowshoes you can find.
  • Binding: My experience is that the binding don’t make that much of a difference unless you are spending the majority of your time traversing an extended hillside. On long traverses in the same direction having a more ridged binding that keeps you foot positioned seems to take a bit less energy.

Interesting Snowshoes

Traction Devices

Ski: Nordic

Skins, Wax, Waxless

Ski: Downhill

When I started to ski a lot the Olin Mark IV the hot ski!  In 2005 I discovered modern shaped skis. They rock! This dates me and indicates that I wasn’t following ski trends  🙂 

Granite Chief or Cosmos in Tahoe for boots

Telemark Tips

Tools&Misc

Ice Axes

IceBox – making igloo blocks the easy way

Goggles… I typically either use DIY glacier glasses or very traditional downhill ski goggles. There are a variety of high performance sun glasses (many with interchangable lens) that provide basic protection. There are several light weight options for people wanting more protection than wrap around sunglasses:

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