In order to spend time and function outdoors in a winter climate, it is necessary to understand the human body’s ability to regulate its own temperature. Because our bodies are naturally suited for a more tropical climate, we need clothing and equipment to keep us dry, warm and safe.
The clothes you choose and how you combine them are both very important. The garments should be designed to allow good mobility and ventilation. The air inside the garment is a key ingredient in the insulation since air conducts the cold poorly. Clothing, gloves and shoes that fit too tightly allow less space for air, and therefore are not good insulators. (On the other hand, if you are wearing very loose clothing it is difficult for your body to warm up the air inside.)
Choose functional fabrics!
Outdoor clothing can be made from different fabrics, as well as a number of different fabric combinations, and are sewn or knitted using different techniques. Each fabric and combination of fabrics has its own unique characteristics. When choosing winter clothing, it is necessary to understand what the advantages and disadvantages of each fibre are in the environment where they will be worn.
Wool is a natural material that has many properties that are useful in a winter environment. The curly, hollow structure of the fibre binds a lot of air, which provides insulation. Wool absorbs moisture and wicks it through the fabric and into the fibre itself, which means that a wool garment feels dry against the skin and provides insulation even when damp. Another benefit with wool is that it does not smell in the same way synthetics do. Wool is excellent in socks, underclothes and middle layers.
One of wool’s downsides is that the rough wool fibres can feel scratchy. Underclothes are therefore usually made of a softer wool from merino sheep. (People with sensitive skin can also have problems with finer wools, so it is important to thoroughly test the layer of clothing closest to the skin. An alternative to merino wool is silk or synthetics.)
Synthetic fibres are created using a chemical process that often relies on oil as one of the raw materials. Typical examples are polyester, polyamides and polypropylene. Depending on how the fibre is designed it takes on different properties, but in general synthetic fibres are good at wicking away moisture while being durable and long-lasting. For this reason, synthetics are often mixed with natural materials, for example in wool base layers.
Synthetics are used for all layers of clothing, from underclothes to shell garments. Synthetic base layers are perfect for physical activities and people who sweat easily and profusely. Middle layers made from synthetics, such as a fleece sweater, also wick away moisture and dry quickly and the curly structure traps air which provides insulation. One downside of synthetics is that they are fast to emit a bad odour and lose part of their functionality if they are not washed frequently. All synthetic garments should also be worn with care around fires and sources of heat; the fabric is flammable and can melt at relatively low temperatures (for example, polypropylene shows signs of disfigurement at 90-100°C).
Cotton is a natural material and in general is the most common fabric used in clothing. But cotton binds moisture, takes a long time to dry and lowers your body temperature, which means it is not a good functional fabric for winter conditions, at least for the layers of clothing that are closest to the body, such as underclothes, socks, base layers and middle layers. That said, however, tightly woven cotton can be functional in outer garments in extremely cold temperatures, for example in an anorak, since the porous nature of the fabric helps release moisture from the body. The general rule of thumb is that “the further away from the body, the better cotton works in a cold and dry winter climate”.
When talking about winter temperatures, reference is often made to the wind chill. The wind chill demonstrates the effective temperature on bare skin at different wind speeds. The wind chill index is excellent for gaining an understanding for the mechanism, but it is still only a theoretical description of a problem – how you react to the cold depends on how you dress.
Several basic rules
• Try to stay dry. Adjust your clothing to the air temperature and your level of activity.
• Use fewer layers of clothing during strenuous activities and in situations during which you believe you will get wet. There will be fewer garments to dry later.
• Save dry reinforcement garments for breaks. Put on your dry change of clothes only when you know you will not get wet again.
• Keep clothing and shoes free from snow and dirt. Brush off all snow before entering someplace warm.
• Think about how you are using cotton so you do not break the multiple-layer principle by wearing the wrong fabric in the wrong place.
Functional clothing not only offers protection from the cold, wind and rain, but also handles overheating and sweating by wicking body moisture away from the skin.
It is important to constantly assess what you are wearing based on the weather, wind and activity. If you ignore your body’s warning signals, perhaps because you cannot be bothered to stop, you can easily have problems later in the trek. This is why it is a good idea to make this a part of your routine when you are on your trek.
Did you know that: Women get cold easier than men, in particular in their hands and feet. This is due to the fact that men normally have more muscle mass than women, which provides better blood circulation and generates more body heat. But when women and men suffer from cold fingers and toes, both should add a warm layer - to their upper body! When too much energy is being used to keep the heart, liver and other important organs warm, the supply of blood to the more peripheral parts of the body shuts down. If the core of the upper body is warm, there is more heat left over for the fingers and toes.
One excellent method for dressing in cold conditions is the multi-layer principle. This principle makes it possible to adapt to the cold, wind and rain. The multi-layer principle divides clothing into four layers, each with its own purpose:
Base layer – wicks moisture away from the skin
Moisture conducts the cold and lowers your body temperature. The base layer should transport moisture away from the skin and keep you dry and warm. In order to function well, the base layer should be rather close to the body. Good base layer materials include synthetics or wool, but cotton should be avoided (read more under Material basics). The no-cotton rule also applies to underwear, socks and bras.
Middle layer – absorbs and wicks away moisture and provides insulation
The second layer should continue to transport moisture away from the base layer while at the same ensuring there is no unnecessary heat loss. The air in the middle layer provides insulation and if temperatures are very low or your activity is stationary, a thicker layer with more air is needed. Fleece or wool sweaters make good middle layers, and it is a good idea to have zippers or other openings that can be opened to release excess heat.
Outer layer – protects against wind, rain and wear and provides insulation
The third layer is a wind and water resistant shell that simultaneously keeps the cold out and the heat from the inner layers in. It also integrates with the other layers by releasing moisture. The outer layer is worn when you are active and it should protect sensitive areas such as your head, throat, wrists, waist and ankles. It should be possible not only to open the neck, sleeves and ventilation openings to release damp heat, but also to open zippers and make other adjustments while wearing gloves.
Modern shell garments with membranes are popular, but in extremely cold temperatures their ventilation capacity is impaired, which means that moisture is trapped inside the garment and, in the worst case scenario, lowers your body temperature. In dry, cold environments, garments made from G-1000 or tightly woven cotton are a better choice since they release some of this moisture through the fabric.
Reinforcement layer – gives added protection when sitting still
Reinforcement garments are put on when resting or when it is time to set up camp. They can be worn both on top of and under a shell garment; an extra sweater or a thermal jacket/trousers with down or synthetic padding are excellent for this purpose. Pull-over garments should be roomy so they are easy to pull over your clothes. They should be stored in the pack where they are easily accessible so you really will put them on when you take a break.
It is easy to assume that a winter trek is synonymous with extreme cold, but in many mountain environments the weather can change dramatically, for example when coastal winds blow in wet snow or even rain. In this kind of unpredictable weather a reinforcement garment can be an ultra-light rain garment that is pulled over the third layer, the working garment, to protect against moisture. In other words, the multi-layer principle is a model that provides a basis for how to think when planning your trek. As with all models, it must be adapted to real-life situations and prevailing conditions.
Application of the multi-layer principle
The multi-layer principle is a flexible method for dressing for the outdoors. Three to four layers provide protection from the cold, wind and rain, and are easy to adjust as your body temperature changes. You are the one who decides, after all it is your sense of well-being that determines what kind of clothes you wear. A fleece sweater, which in reality is a middle layer, may be the perfect outer layer on days with mild winds and comfortable temperatures, and as spring unfolds you might only need to wear a base layer. In other words, the multi-layer principle is a theoretical model for how to dress functionally, but it is not a hard and fast rule.
Potential multi-layer solutions in different situations
• High intensity activities: base layer + uninsulated outer layer
• Mid-intensity activities: base layer + insulated outer layer
• Low intensity activities: base layer + middle layer + outer layer
• Breaks, resting and emergency situations: the same as low intensity but reinforced with a middle and/or outer layer
Be proactive and adjust your clothing regularly based on the weather, wind and activity! If you wait – because you are tired, lazy, not in the mood or do not want to bother your companions – the group can have problems later.
Remember to help your garments breathe! Open the neck, cuffs or ventilation openings when you are active and warm. This will allow you to release excess heat, which in turn decreases the risk that the inner layers will get wet and lower your body temperature.
First ventilate – then reinforce
When you stop to take a break, it is often a good idea to release excess body moisture before you put on your reinforcement garments. In reality, this might be unnecessary to point out since we often, by instinct, unzip our jackets and maybe pull off our hats and gloves and rest for a moment before we put on our thick down jackets. Whenever you have a chance, for example when sitting in your wind sack or lee side, you should take off your shoes and socks for a moment, and preferably even change your socks. This will make a big difference when you are on long treks.
Gloves and hats
The multi-layer principle does not only apply to the body, but also to your head, hands and feet. When your body gets cold, it takes care of the most important body parts first: the head and inner organs. Blood flow to the extremities decreases.
Different hats for different activities
The part of the body that loses the most heat is your head, so it is important to be able to easily change your hat depending on how active you are. The collection of head gear for your winter trek can consist of a balaclava, a windproof hat or a trekking cap with fold-down ear flaps. Make sure that your back-up hats are easily accessible, for example in a pocket, so you can switch when your activity is over. Release excess heat by taking off your hat. In really cold conditions you can layer your balaclava and hat/cap.
The hood of your jacket fulfils and important function. A good winter jacket should have a large hood that protects your face and moves with your head. It should have a windsleeve and/or fur edging. The fur helps to stop the wind and creates a protective cushion of air around your face.
Never bare hands
Your hands are your most important precision tools. If you have difficulty using them, because they are too cold or stiff or because of painful chapping, you will face some serious challenges. The multi-layer principle when applied to hands requires:
• a thin, five-fingered liner-glove closest to the skin
• a lined five-fingered working glove as a middle layer
• a large, lined mitten that covers your wrists with a shell/outer mitten.
It is best if the five-fingered gloves and shell mittens are constructed so you can remove the lining – not only because it is faster to dry them separately, but also because it is easier to vary the degree of insulation around the hands. The shell gloves should be large enough for you to wiggle your fingers even when wearing five-fingered gloves and the liner underneath (when wearing them without their removable lining).
Bedtime in a hat and gloves
Your head and hands need to be warm even when you are in your sleeping bag. A thin hat, without tassels or anything else that gets in the way, and a pair of knitted gloves usually are all that you need.
Several tips for warm hands:
• Never touch metal directly without gloves
• Never blow moist, warm air into your mittens/gloves
• Attach your gloves to your jacket using straps so you do not lose them in bad weather
• Choose the proper glove for each activity and protect your gloves from moisture and injuries
• Bring along an extra pair of liner-gloves • Use the cuffs of your sweater as reinforcement at the wrists
• In an emergency, use a sock to replace a lost glove
• Take care of your hands: wash them, massage them and use hand cream, for example before you go to bed