One of the questions we are often asked is how to
regulate temperature, stay warm and dry while walking or climbing, in
a variety of weather conditions, without having to buy a complete set
of clothing for each season. Although most serious walkers and climbers
have a wide range of clothing to suit different conditions it is possible
to have a general set to cover most eventualities in spring through autumn.
The theory behind this is called the Layering System,
or less well known by the name of "Onionskin layering". It is based on the
fact that several thin layers of clothing will keep you warmer than one
thick layer. This is because they trap a larger volume of air, and it is
this static "reservoir" of air that insulates you from the cold. Not only
that but you have a greater degree of control over the level of insulation
by adding layers if you are cold or removing layers if you are too warm, far
better than having a choice between shivering in a shirt and roasting under
a thick sweater! This is very important because sweat is the enemy in cold
conditions as it leeches heat from your body and dehydrates you if you
produce too much.
More work done in greater comfort with less sweat
produced is the holy grail of layering. The layers are known as:
1. Base Layer
Can be a cool shirt with UV protection in hot
summer conditions or a thermal insulation layer for winter. It must
be comfortable as it is next to your skin all day. This is the hardest
working layer as it has to wick all your sweat to the outer layers
and is worn the longest.
2(a). Mid layer
Usually a microfleece or similar item. Thin,
comfortable light insulating layer. A pullover microfleece with a
deep neck zip is my usual choice to allow ventilation if required
and can be zipped up to provide greater insulation.
2(b). Outer layer
Thicker, medium weight fleece for optimum
warmth with minimum bulk. The mainstay of the cold weather layering
system, a full zip version allows more options for insulation/ventilation
balancing.
3. Shell
This should be a waterproof, windproof, breathable
jacket and trousers (if required). Separates you from the harshest
weather conditions allowing a stable environment for the lower layers
to perform at their best.
There are a few vital properties that all layers must
have for the system to work at its optimum. They must be lightweight, fast
drying and, most importantly, have wicking properties. This is the ability
of an item of clothing to transport moisture (usually sweat), from the surface
of your skin to the outside of the fabric, if all layers do this the sweat
will be wicked through them and your breathable shell jacket to be dispersed
into the atmosphere. The problem occurs when there is a "weak link" in the
chain, that is, a layer which doesn't wick, and acts like a sponge and
retains most of the moisture it soaks up making you feel uncomfortable
and cold. Cotton is the main culprit for this and it's for this reason
that cotton is best used as a fabric to keep you cool in very warm conditions
and nowhere else. Otherwise all clothing should be made of synthetic or
woollen fabrics. I find fast drying synthetics best.
I have listed my Spring-Autumn and also my Winter
layering systems as a guide to what you should be looking to take into
the hills with you, but these are only my preferences and you should
adjust the list to suit yourself. Some people feel the cold more than
others or overheat more easily, you know yourself better than anyone
else, so be creative! Remember, the more comfortable you are the more
enjoyment you will get from the outdoors. Dress for the worst weather
expected, you can always take off layers and pack them away, but if you
don't have them with you there is nothing you can do.
Spring-Autumn
Base- Shirt or t-shirt, lightweight trousers or shorts.
Mid Layer- Lightweight /Microfleece or medium weight fleece.
Shell- Lightweight waterproof jacket.
Winter
Base- Thermal base layer (long sleeved, high neck), thermal long johns.
Mid Layer- Microfleece, lightweight trousers.
Outer Layer- Medium Technical Fleece.
Shell- Technical Waterproof Jacket & Trousers.
Extras- Thin liner gloves, waterproof & insulating overgloves or mittens, hat, necksock or scarf.
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