Do not forget about yourself in the cold
Extremely cold temperatures can force your entire body to go over into “survival mode” and everything that you think about and do becomes focused on staying warm. This is, of course, the right thing to do. But to feel good in the long run, you have to take care of yourself. If you make sure that you continuously recharge with energy and liquids, use your wind sack during breaks to get the best rest possible and stay dry and reasonably clean, you will have a better chance of finishing your trek in good physical condition. (And a positive side effect is that some of the things you should do also help you stay warm.)
A normal, naked human body functions best when the air temperature is 27°C. One way of defining the word “cold”, then, is any temperature below 27°C. Below this temperature we need to be proactive, whether by adding clothes for protection, going inside or moving around to raise our blood circulation. Wind and rain dilute our perception of the cold.
There is a saying in Greenland that “if you sweat, you die”. This might be a little drastic, but it illustrates a point - when moisture enters the picture, frostbite often becomes an issue, even at temperatures above 0°C. Water conducts heat 25-30 times better than air and rapidly transports energy away from the body. (Air, on the other hand, is a poor heat conductor and provides insulation – a characteristic that sweaters, down jackets, sleeping bags, etc., make the most of.) This is why sweat, snow and water are actually a threat to your well-being, particularly if you are on a long trek and are unable to dry your clothes and equipment at the end of the day.
Wind and wind chill
When the wind is not blowing and you are standing relatively still, the air around your body warms up and acts as a layer of insulation. If the wind starts to blow, this warm air is pushed away by new, cold air. Your body reacts by once again warming up the air around you. If this continues for a long period of time, your body temperature will drop.
The more the wind blows, the cooler you become. At a temperature of –15°C and winds of 8 metres/second, the wind chill factor on your bare skin is the same as wind-still conditions at –34°C. This relationship between the wind, temperature and effective temperature on your bare skin is illustrated by the wind chill index below.
Drinking is important for many reasons, but it is particularly important in the winter since you lose large amounts of liquid in cold temperatures. Staying hydrated and maintaining your blood sugar levels are prerequisites for being able to perform both physically and mentally. Dehydration is one of the most common reasons your body starts to shake. Dehydration makes the core temperature in your body fall and your heart rate increase, which in turn requires your body to use more energy to stay in motion and lowers your ability to perform. Insufficient hydration combined with the wrong gloves or even bare hands can cause chapping – which in a worst-case scenario makes it painful to use your hands.
Get your water from an open, running source if at all possible. You might need to melt snow at times, so you should make sure it is not dirty or potentially could contain something that can spread bacteria. Since snow is porous and contains a lot of air, the volume will decrease dramatically when it is melted. Pack the snow down hard to get the most liquid possible. If you are out on a longer trek, you need to remember that snow and the water from mountain streams do not have many minerals. In order to keep your muscles working optimally, you need to supplement your meals with dietary supplements (there are usually sufficient amounts of magnesium, and sometimes potassium – sodium chloride, in the food).
• Drink small amounts often.
• Drink at least 4 litres per day.
• Drink warm drinks (at least 20°C), and preferably drinks that are slightly sweetened – this helps your body absorb the liquid and supplies your brain with blood sugar.
• Avoid quenching your thirst by eating snow - this cools down your body.
• Carry a thermos or water bottle close to your body in the extreme cold to prevent the contents from freezing.
As little as possible should get wet
One good basic principle is that, when you are out on a trek, as little as possible should get wet. This applies to both equipment, such as backpacks and sleeping bags, as well as clothing worn close to your body, such as shell garments, middle layers, shoes and gloves. As you have learned, water conducts the cold, which represents the single greatest threat to your welfare during your winter trek. Since there will be limited opportunities to dry your belongings, you need to focus on prevention and try to keep them dry.
There are many small tricks you can use to keep the moisture at bay, but ultimately you need to pay attention to both the moisture you generate yourself by sweating and external moisture in the form of melting snow. Here are several tips to help you stay dry:
• Always adjust your clothing to the air temperature and your activity level. The ideal temperature is when you are neither cold nor sweating.
• Save your reinforcement garments for breaks and emergency situations.
• To keep your gloves dry when you are active, for example when digging a bivouac or wind protection, use a shell glove with only a thin wool glove underneath. Another variation is to take the lining out of your five-fingered gloves and only use the leather part of the glove.
• If the midday thaw is making the snow melt on your boots and moisture is finding its way inside, use snow gaiters or overboots to create a shell that ventilates better.
• Brush snow off your clothing, shoes and backpack before you go into a warm space, for example a cabin.
A safe haven for emergencies – or a comfortable place to sleep in the snow
The idea of sleeping in the snow can be met by scepticism by people who have never tried it. The fact is that a well-built snow bivouac is an excellent alternative for accommodation. It is quiet and protected from the wind and, compared to staying in a tent, it is also relatively warm since the temperature in the bivouac usually is only a few degrees below freezing. However, the bivouac can become a necessity if you are trying to seek shelter from bad weather. Go out on a nice day and practice digging one. Just like for everything else, practice makes perfect – and when the wind is howling might not be the best time to consider different digging techniques.
An emergency bivouac must be built quickly. Skis, poles and a wind sack may supplement the basic construction material, snow. It is also important to use the probe to determine how deep the snow is. One basic error that many beginners make is that they dig the ditch and then try to prepare the barrier. It is much better to form the barrier while you are digging – a technique which means that the longer you dig the more protected you will be.
• The simplest type of emergency bivouac is a small hole that a person can lie in, which is often the only alternative in places where the snow is not very deep. Skis, poles and the wind sack are then placed across the top of the hole. It is not particularly comfortable, in other words, but at least you will be protected from the wind and snow.
• If the depth of the snow allows it – you will need at least 1.5 metres – an emergency bivouac that you can sit in is a more comfortable alternative. Skis and poles are placed across the top like beams and a wind sack is laid on top. Put snow on the roof and use a backpack as the door.
• If you can find a snow drift, it will be much easier to dig. When building an emergency cave, you take advantage of the slope and dig "inwards", using the same technique as when building a real snow bivouac. An advantage of this type of emergency bivouac is that it can be extended if you need to stay for a longer period of time.
Practice is the only way to learn
It is, of course, impossible to learn how to build a bivouac by merely reading some instructions. You need to practice out in the snow, preferably under the guidance of someone with experience. Many mountain stations arrange courses and independent organisations also offer mountain safety courses that include how to build a bivouac. Take one of these courses and then, on a beautiful day, go out with your family or friends and build a "snow cave".
Even if we cannot go into detail here about how to build different types of bivouacs, there are several safety aspects that are worth highlighting:
• Never dig in a high-risk avalanche area. While digging, you need to make sure that your equipment is not lying somewhere where it can be easily buried by collapsing snow.
• If you are digging in a drift, choose a high location so you can see over the edge. If it snows during the night, you will be able to get out by digging straight up. If you are further down in the ravine and several metres of snow drifts in, you will not have much of a chance of digging yourself out.
• Make some ventilation holes, about 10 cm wide, straight up with a pole. Let the pole sit in the hole so it can keep the hole clear if it snows. The ventilation holes are to allow fresh air to come in and regulate the temperature.
• There is enough oxygen in the bivouac; oxygen is found in the space itself and in the surrounding snow. However, if you stay for a longer period of time, you should occasionally scrape away the ice that builds on the wall and the inside of the roof to prevent a deterioration in the ventilation.
• Building a "gothic style" bivouac, i.e. with an arched roof, decreases the tendency of the snow to sink inwards in warmer temperatures.
• If the inner temperature of the bivouac becomes so high that the snow starts to melt, you should expand the ventilation holes or open the entrance so the temperature returns to below freezing.
• Due to the risk of carbon monoxide poisoning, you should not prepare food inside a snow bivouac. Heat water and fill thermoses and hot water bottles outside.
In addition to the tips listed above, you should remember to try to keep your clothes and equipment dry and free of snow. For example, it can be a good idea to place a ski next to the wall to make sure that you do not roll into the wall while sleeping and get the sleeping bag wet.