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How to stay warm in the UK mountains


The layering system

The layering system can be a complex one to get your head around. Typically it is a three layer system, but with all the different brands, types of outdoor clothing and materials on the market, it can be quite difficult to decide on the perfect layering system. This isn't going to be a 'What to wear for UK climbing' or 'The best jacket for hill walking' type of article. Instead, in this article we will be looking at why we get cold, how we can avoid this and a brief look at the layering system used typically in the UK mountain environment.


We all know the UK mountain environment can be unpredictable: it is not uncommon to encounter all the seasons in one day! For example, I have climbed in a down jacket in July but then walked off the top in a T-Shirt yet sat for lunch on a summit in February in just a base layer only to be in full waterproofs, hat and gloves an hour later. You can't ever odds it.


Winter is fast approaching and it is at this time of year most people pack away their climbing rack and their walking boots to await warmer weather in the spring, but this needn't be the case! Knowing how to stay warm in the mountains and why we get cold can keep you hill walking and climbing all year round. (Plus it is vital knowledge if you decide to progress to winter walking and climbing in the future.)


Until you have acquired the skills to walk and climb in the snow and ice, those higher level slopes are still a bit out of reach, however the lower slopes of the mountains, fells and moorland are more than accessible in the winter. You just need to be in the know when it comes to keeping warm.

 

Why do we get cold?


I'm going to take you back to your secondary school physics class. Now, stay with me here, I won't get too geeky (I'm not a physicist)! Understanding how heat transfer works can help us understand why we get cold. The three types of heat transfer we will look at are:

  • Conduction

  • Convection

  • Radiation


Conduction

Conduction is the process of losing heat through physical contact with an object. Heat will transfer from a hot body to a cold body until a state of equilibrium is reached (both are the same temperature).


In our terms, if we are to sit on a wet rock or the ground when taking a rest, our body heat will be transferred to that rock or the ground, effectively reducing our body temperature. On top of that, being wet speeds up the process of heat transfer from our body to the environment: water conducts heat 25 times better than air, meaning it will conduct heat away from your body 25 times quicker. Our natural cooling system, sweating, helps us regulate temperature. If we get too hot, we sweat. Helpful in the summer to keep us cool, but this can work against us in the winter or cooler temperatures and cool us too much. If we are working too hard walking up a hill and over heat, causing us to sweat too much, this sweat can soak our layers keeping the moisture close to the skin and continuing to cool us.


Winter walking in Scotland
Sitting on cold surfaces for too long will cool you down quicker if not insulated from the ground.

On the subject of sweat and evaporation, any exposed skin on our body will lose heat much quicker, especially if wet. Our skin is the largest organ of our body, covered in sweat glands. The more exposed skin to the elements, the quicker the cooling process.


Afraid of stating the obvious, sweating isn't the only way we get wet in the outdoors. Rain, sleet and snow can cause us to lose that vital body heat we have worked so hard to generate. By staying as dry as we can, we can stay warmer.


Key tips to reduce conduction:
  • Avoid sitting on the ground and rocks etc. without insulating yourself from the object. Carry an off cut of a foam mat to sit on that can slide down the back of your rucksack and is big enough to sit on.

  • Avoid brushing your layers against wet surfaces (i.e. tree branches, wet rocks etc.) Keeping your layers dry can help reduce heat loss through conduction, especially if your outer layer isn't waterproof.

  • Avoid overheating to reduce sweating. This helps keep your base layer (next to skin layer) dry. Reduce your walking speed or vent your layers (See convection below).

  • Wear a non-absorbent and tight fitting base layer to aid sweat evaporation, moving it away from your skin (wicking). Cotton absorbs water so avoid cotton base layers. Natural wool (Merino) or synthetic base layers work best.

  • Cover exposed skin. It's a myth that we lose most heat through our head. However, it is generally the most exposed part of our body when out in the hills and mountains. Wear a hat and/or a buff to cover as much skin as possible to reduce heat loss. Keep your hands warm by wearing dry gloves (carry a spare pair to replace wet gloves). Mitts keep your hands warmer but at the cost of reduced dexterity.

  • Avoid exposing skin by tucking your base layer in to your trousers. This stops your lower back from being exposed if you need to bend over to get something out of your rucksack.

  • On the subject of covering exposed skin, insulate your whole body from the elements. Don't go wearing shorts and cover your core with five layers. You will lose more heat through your legs than your head in this example!

  • Now this might seem an obvious one, but you'd be surprised. Keep your layers dry by wearing a waterproof. Put it on at the first sign of precipitation or ideally, before it starts!

  • Put your hood up! Water can enter through the top of your jacket and get absorbed down through your layers making you wet (common cause of people saying their 'waterproof doesn't work')

Cold day on a navigation course on Dartmoor
Covering as much exposed skin as you can will keep you warmer and protect you from the elements.
 

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Now, back to the article!

 

Convection

For our example, convection is the movement of air (can be liquids too), transporting heat energy from hotter areas to colder areas.


Our bodies generate heat and we can contain this body heat by wearing insulation layers. We want to keep this heat close to our core and contained in our layers, but the wind has other plans. The movement of air (wind) can strip away our lovely little layer of warm air, reducing our body temperature. We need to protect ourselves from the wind by wearing windproof layers, such as a waterproof or softshell, to avoid our bubble of insulated air being transported away from our core. Think along the lines of opening your windows at home to allow air to circulate through your home.


However, there are times when convection, using the wind to transport heat away from our bodies, can work for us to keep us from getting cold. As mentioned above in conduction when discussing avoiding getting wet through sweat, we can vent ourselves to avoid overheating, reducing sweating and keeping our layers dry.


Guided scramble along the CMD Arete, Ben Nevis
Vent those layers by unzipping to allow some heat to escape to avoid overheating

Key tips to reduce convection:

  • Tuck in your base layer, as with conduction. This helps reduce the movement of air out the bottom of your base layer by stopping the wind being able to get to your body.

  • Wear a buff, or similar, around your neck to stop air being forced out the top of your jacket.

  • Tighten drawcords around the waist and neck and fasten cuffs. This stops air movement through your layers, which contain your precious warmth.

  • Avoid baggy layers (see how layering works below). More air around your core requires more energy to heat it (see radiation below). More air in your layers means it is easier for that air to be displaced, even through regular movement, which transports that warm air away from where it is needed. In addition, the wind can press against your insulation (compressing it), acting as bellows, forcing the warm air to move inside your layers.

  • Use pit zips/body zip when necessary to avoid overheating.

  • Adjust clothing by taking off a layer to aid venting.

  • Have a layering system which you can add to so you are not losing that layer of warm air by removing a key layer. e.g. an outer insulation layer that can fit over your waterproof/softshell.


Radiation

An example of radiation is the sun heating the earth, where electromagnetic waves that permeate out from the heat source. This heat can be absorbed, reflected and transferred into other objects. Our bodies are similar in the way in which we burn energy and produce heat which radiates out, warming the environment in close proximity to our skin. Normal body temperature is around 37 degrees Celsius. We can generate more heat through activity; walking up hill, running etc. We want to trap and contain this heat and not let it escape whilst outdoors in the colder months.


Guided walk up Cribyn, Brecon Beacons.
Walking up steep hills generates a lot of heat!

Animals use fur/hair/feathers to help contain this heat by trapping small pockets of air next to the skin. We can do the same, 'goosebumps'/hairs standing on end, but this is not as effective as the animal kingdom. Instead, we wear clothes which help trap a small layer of warm air that we have heated through our body's radiation of heat. The typical outdoor layering system (see below) utilises different types of insulation to contain our bodies warmth. Think along the lines of double glazing and insulation in the walls of your home.


Like with a fire, your body needs fuel to burn to create energy. As a fire uses its fuel, it gradually reduces its heat output. Your body is the same. To continue to radiate heat into our layers, we must continue to fuel ourselves by eating throughout the day. The same is true for keeping hydrated too. We need water to help digest our food, in turn converting it into energy.


Lacking fuel and being dehydrated causes us to become tired and exhausted. In these instances, we have burnt through our energy reserves and can no longer continue at a steady rate. Becoming tired means we walk slower which in turn reduces the heat generated by our muscles. If we stop entirely, whether through taking a break or an emergency, our heat production also decreases, causing us to get cold. Once cold, it takes more energy and time to reheat and to maintain a consistent core body temperature (Think the difference between boiling a kettle from cold than when recently boiled). If you don't have that energy, you will gradually get colder and colder and struggle to warm back up.


Key tips to improve radiation:
  • Eat and hydrate regularly. Pre-fuel and hydrate the night before, have a good breakfast and eat snacks regularly during your activity. Have snacks easily accessible, in pockets or the lid/side pockets of your rucksack to encourage regular eating. Use a hydration bladder for easy access to water or a water bottle in a side pocket, somewhere easy to access.

  • Take regular breaks to ensure the above.

  • Warm up gradually. The age old, 'Start bold, start cold' rings true in all aspects of mountaineering and climbing. Start your walk in light layers, but with the option to add more when needed. For example, set off in a base layer and a light fleece/windproof layer (if conditions are good) or a waterproof (if wet). You will soon warm up once you get going. You can add layers on top if you are still cold after a while (or under your waterproof). Starting off too warm will mean you start to overheat quickly, leading to sweating and getting damp. (see conduction above).


Guided walk up Cribyn, Brecon Beacons, with Pen Y Fan in the background.
Take regular breaks to eat, hydrate and top up those energy levels.

How Layering Works


Your layering system needs to be versatile and adaptable to the conditions you are likely to experience in the hills and mountains. It should keep you warm and dry throughout the day.


The typical layering system we see in the UK consists of the following:

  • Base Layer: Top (some people also like bottoms in the form of legging style)

  • Mid Layer(s): Usually just the top

  • Outer Layer: Top and trousers

  • 'Belay Jacket'/Warm Layer: Usually just the top


Base Layer: A tight fitting layer designed to wick sweat away from the skin (can act as a thermal too). It is usually made of synthetic material or wool (Merino). Styles include lightweight T-Shirt through to thermal zip-neck and everything in between.

  • Tight fitting, next to skin.

  • T-Shirt style for warmer conditions

  • Long sleeves for colder temperatures

  • Zippered neck to help with ventilation (usually with high rounded 'collar',)

  • Can get hooded style for really cold weather

Climbing at Swanage
Long sleeved, zip neck base layers are versatile and in this instance used as a stand alone layer.

Mid-layer(s): Fleece or synthetic insulation. They trap a layer of warm air in their material or reflect it to keep it close to the body. Lots of different styles including gilets, jacket style, hooded and various zip alternatives (Half zip/full zip). Usually a couple mid layers are worn or carried.

  • Depending on conditions, usually 1 or 2 worn.

  • Should be fitted but not too tight. You don't want to compress the insulation reducing its effectiveness.

  • Incidentally, you don't want it too big allowing air to move around and escape.

  • Different brands fit different body shapes, try on different brands to see which fits your body shape.

  • Think about different styles that complement each other. Light fleece jacket and a synthetic gilet is more versatile than one thick hooded fleece.

  • Too many hooded mid-layers can affect how the layers perform (difficult to do all the zips up) and how they layer over each other.

The layering system
All of the mid-layers!

Outer Layer: Generally a waterproof and windproof layer. Usually just a waterproof but softshells and windproof layers are worn when it's not wet.

  • Waterproofs (referred to as Hardshells) are, as the name suggests, waterproof but also windproof.

  • Buy a size up so it doesn't compress the insulation underneath.

  • Being waterproof, they generally don't allow for much moisture to escape either (contrary to them being 'breathable'). Other outer layers 'breath' better and may be a better option if it isn't raining.

  • Softshells are more breathable than a hardshell but are not great in wet weather. Reserve for cold, dry days.

  • Windproof jackets are lighter and more windproof than a softshell but not waterproof like a hardshell. They are good for putting on when stationary if the weather is dry.

  • Softshells tend to be 'warmer' than a windproof as a stand alone layer.


Climbing on Scafell Crag in grim conditions!
When conditions are grim, keep the elements away from your insulation using a hardshell

'Belay' Jacket/Warm Layer: An oversized synthetic jacket that fits over all your layers. Used when taking a break, belaying or in an emergency.

  • Oversized to be able to fit over ALL your layers (including outer layer)

  • Because of the damp nature of the UK climate, usually synthetic insulation.

  • Synthetic insulation retains it's warmth when wet. Down insulation doesn't!

  • Down, weight for warmth, is better than synthetic insulation (only when dry!)

Climbing Clogwyn Left hand (V,5) Clogwyn Du, Eryri
Throw on that warm outer layer when stationary or belaying whilst climbing

Alternative suggestions to layering


There is no hard set rule as to how to layer. We refer to fleece as a 'mid layer' but it can easily be worn as a stand alone layer if conditions dictate; I.e. it's a cold but windless day. Below are some ideas which I would encourage you to experiment with:


(Assume a long sleeved base layer is being worn. Hat and gloves too. Waterproofs always carried)

  • Hooded fleece with synthetic gilet on top - (Cold, dry conditions with light breeze)

A versatile system that allows for adding another layer (the gilet) without removing a layer. Carry an outer layer to add to the system if the wind picks up.


  • Softshell with synthetic gilet on top - (Cool, dry, windy conditions)

You could substitute softshell with windproof. This would work if you have set off from the car park (start bold, start cold) and want an extra layer to put on. Instead of taking off the softshell/windproof, layer over the top.


  • Fleece jacket with Softshell on top (carrying gilet as added insulation) - (Cold/Very cold, dry, windy conditions)

Cold/very cold, frosty day walking across the tops. Lots of ups and downs. The gilet can be added for extra insulation to the core without exposing yourself to the cold. Gilet can be removed on the ups.


  • Synthetic gilet and waterproof (carrying fleece as added insulation) - (Cool, wet conditions)

Possibly steep walk up hill in wet conditions. Avoiding overheating by wearing minimal layers but keeping dry with the waterproof. Fleece for added insulation for later in the day.


  • Light fleece, synthetic gilet, synthetic jacket, softshell, belay jacket - (Bloody freezing, dry and windy conditions)

From experience, standing around not doing much activity. Typical layering of a rock climbing instructor running a bottom rope climbing session at the start and end of the year! Windproof/waterproof on standby! Hot coffee in a flask too.


Climbing the Old Man of Hoy, Orkney
Synthetic gilet over a softshell when climbing is a versatile system, allowing freedom of movement and good regulation warmth.

Final tips to staying warm

  • Try all the above key tips!

  • Look at the weather forecast the day before and in the morning before you leave. This should help with decision making as to what to wear/how to layer.

  • Carry a flask of a warm beverage of your choice (Hot Ribena is a game changer!)

  • Waterproof gloves/mitts help keep your hands warm. You can buy them as insulated gloves or just the shell to layer over your thermal gloves.

  • You can buy windproof shell gloves too, but these are not waterproof.

  • Also, waterproof hats! I've never tried them though. Let me know if you have and how you got on with them.

  • Hand warmers! Put them in your pockets or in a chalk bag if climbing (An MCI showed me that tip!)

  • Carry a group shelter. These are great to get yourself and the group you are with into when stopping for lunch and for emergencies. They cut the wind out and warm up inside with a group of people generating body heat! My only issue is you may not want to get out of them!


Demonstrating how to use a group shelter
Group shelter are fantastic bits of kit to help keep you warm and dry on lunch breaks and in emergencies!
 

Before I round up this article, I just want to emphasis that everyone is different. Some of us run hot, some of us run cold. I know I can get away with less layers than most people in the hills and mountains as I generally run warm. And I'm not usually a fan of recommending specific branded clothing as it's all subjective to the user's build, their activity, financial situation and genetics. What works for me might not work for someone else.


In a future post, I will go into more depth and detail about the layers on offer to us on the market, what I wear and alternative suggestions. But all this should be taken with a pinch of salt!


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Try out what you already have, before going out and buying more layers and put into practice some or all of the tips highlighted in this article. You may find you don't need to buy more and save yourself some money for your energy bill!


I hope you have enjoyed the hints and tips in this article, please feel free to leave your tips in the comments and share this post on your social media! Tag @attheedgemountaineering or use #attheedgemountaineering so we can see your post!


Trekking the Salkantay Trek, Peru
What works for you may not work for someone else.

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