Updated: Mar 28, 2020
What do you do when you are cold? Most would put on another layer, a jumper or a fleece.
What if it is really warm? Do you wear less clothing which is lightweight to help us stay
We already have a good idea about layering clothing to suit our needs and environment but there is a little more to it than we first think.
What is the Layer system?
The layer system is the method of which we put on clothing for outdoor Adventures.
Each layer has a job to play and works in combination with the other layers to provide effective protection from the environment your in.
If the layer system is working efficiently it will have an impact on the energy you use to either keep yourself warm or to cool yourself down.
It’s a much better way to dress for outdoor activities, rather than putting on one large jumper and overheating when you are active it allows us to regulate our bodies temperature through the ability to add or remove layers, adapting to the energy we are putting in to the activity and what the weather and environment is throwing at us.
The types of clothing and which layers we wear depend on the activity we are participating in.
For example, a climber may want thinner, more light weight layers to help him or her regulate their temperature but also allow them the freedom to move and position themselves while climbing.
A hill walker, on the other hand, may want several good layers to keep them warm but without sweating to much and also staying dry from rain.
For this blog post we are going to focus on the fundamentals of the layer system and the roles each layer does. It is then up to you to experiment and play with these to find what works best for you. There are no wrong or right answers here, just the feedback you get when you are out on your Adventure.
The layer system is made up of 3 layers and accessories. These layers are,
Base-Layer, Mid-Layer, Outer-Layer and Accessories.
Why is the layer system important?
We can face some tough conditions on our Adventures and it’s important make sure we are able to look after ourselves and the people we may be with.
If we are worrying about our condition or if we are becoming uncomfortable because our clothing isn’t working we lose focus on enjoying the Adventure we are having and it can quickly become a misadventure.
Having the ability to regulate our body’s temperature and adapt to the prevailing conditions allows us to prevent the situations that can lead to life threatening conditions.
Overheating, either through our own physical exertion or from the environment we are in, causes us to sweat.
Our sweat makes our clothes damp.
This moisture, coupled with warm air escaping from your body, being replaced by cold air, say through a breeze or the wind can cause your body temperature to drop.
In cold or wet and windy weather this can lead to serious issues and cause you to become a casualty.
If your wearing to much, or wearing to little and exposed to the sun and heat for too long in hot environments, then again, you can overheat and become a casualty very quickly.
Understanding how to use the layering system and the types of clothes in each layer helps to prevent any issues so we can enjoy the Adventure we are on!
How does the layer system work?
Each layer has its own job to do. The big picture is to create and trap a layer of warm air against your body to act as insulation but also to remove (or wick) any moisture away from our bodies so it can evaporate quickly and easily. It also is designed to protect us from the outside coming in, for example from the rain and the wind.
So we can really get our heads around the role of each layer, it is first really useful to understand how our bodies warm themselves and how we lose heat. This can be a fairly interesting and in-depth subject so in the interest of keeping things brief, our bodies warm themselves by burning calories from our food and so we need the calorie intake to keep ourselves warm.
Now consider that you may need more calories to keep your energy levels up while participating in an outdoor activity and you quickly see that you need a few more calories while outdoors then when you are at home.
Our bodies cool through 4 methods, these methods are,
Convection, Conduction, Radiation and Evaporation.
Convection is what happens when we stand in front of a fan on a hot day.
Our body heats the air that it is in contact with, that air is then replaced with cooler air which is then heated again and replaced again and so on…
The cooler air takes away the warm air around our bodies and so we begin to feel the effects of the cooler air, this is why it is really nice to stand in front of a fan in the summer, but its not much fun in the winter.
In order to prevent the warm air being lost we need to do 2 things.
1. Trap the hot air so it doesn’t escape, ideally keeping it next to our skin, and
2. Protect against the cooler air from taking the warm air away.
This cooling effect is intensified with the addition of moisture and this is why our bodies create sweat. This leads us to the next cooling method that is…
Evaporation occurs when we sweat which then dries.
Our bodies create sweat for a number of reasons, the reason we are focused on here though is from physical exercise through an Adventurous activity, although there may also be some times that push our limits and we sweat due to being excited or a scared too.
The water in our sweat heats up and turns in to water vapour, which removes the heat from our skin cooling us down.
This is perfect in warmer environments as we want to regulate our body’s temperature to stay cool but we need to be careful about how much we sweat as it can lead to dehydration, cramps and other serious conditions.
In colder environment we want to reduce the amount we sweat to reduce the cooling process and keep ourselves warm.
Layers in the layer system carry the sweat away from our skin so it can evaporate, we call this wicking and this is why we look for clothing that is ‘breathable’ as it allows the sweat to be wicked away but it still protects us from things like the sun or the cooler air if we are in colder environments.
Conduction happens when we touch something that is colder than ourselves.
A classic example is when we touch a metal pole in the winter, with no gloves on. Our body transfers heat to warm the colder object to match our own body temperature.
We lose heat this way in a number of ways and depending on the activity we are taking part in depends on what we are losing our heat too.
For example, a hill walker will be walking across cold ground, they may be carrying walking poles and may sit or lay on the ground to rest, a climber will be touching rock with their hands and a paddler will be sat or knelt in a boat.
To reduce or prevent the heat being lost through conduction we need to create a barrier to insulate ourselves from the object we are touching.
This method is transference of heat with the environment that we are not directly in contact with like convection or conduction. It is the this method that allows the sun to warm the earth.
As human we naturally give off heat in to our environment, for example it is thought that we lose a huge amount of heat through our head that radiates heat out in to the environment around us.
When I was in school we were told we lose between 40% and 45% of our body temperature through our head and it was very important to wear a hat in cold weather.
This has actually been found to be not entirely true and while we do lose a significant percentage of body heat through our head it is other areas of our bodies that we should be aware of such as our legs, bum and our torso.
To reduce this heat loss we use our clothes to trap the heat and to minimise the amount of heat we give off.
What are the layers in the Layer system?
Now we know the ways we lose heat and how we create heat lets take a look at the layers we can use to reduce and prevent heat loss and wick moisture away from our skin.
This layer is the first one we put on, after our underwear, and is worn next to our skin.
Its job is to trap a thin layer of warm air next to your skin but it also wicks sweat away from your skin when you are working hard.
Good items of clothing for this layer are things such as long or short sleeve breathable t-shirts, leggings or tights, sports tops or purpose made base layer clothing.
Avoid any cotton t-shirts or leggings as cotton holds moisture and keeps you cold. It also takes a longer time to dry compared to other fabrics and therefore needs more energy to dry it.
Ideal fabrics for this layer are Merino wool or bamboo which is becoming more and more popular, natural fibres are better as they hold the heat longer when you stop moving.
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