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Why do i get cold and how can i keep warm?
A resting healthy adults core body temperature is 37
oC or 98
oF. A change of 2 degrees in either direction is very serious, 5 degrees fatal if not countered. Understanding how to mitigate heat loss in cold weather is knowledge that every outdoor enthusiast should have. It may well save your life!
How does the body protect against the cold?
Most
people are unaware that they are loosing body heat until effects
manifest themselves physically such as the cooling of the fingers and
toes. At this point the body has already kicked in its survival process. When your body core temperature starts to drop, the body diverts blood away from the skin surface and peripheries and keeps it circulating around the bodies core to protect the major organs. If you keep on loosing body heat then you will start to shiver. Shivering is basically the oscillation of muscle mass which results in the generation of heat. Hormones will also be released to increase your metabolism and thus heat generated.
Further exposure to the cold
The Science behind loosing body heatThe loss of body heat to the environment can be due to four main processes:
- Radiation - Basically this is the transfer of energy between objects of different temperatures. Our bodies are often a lot warmer than the outside temperature so we radiate heat. This is compounded by the fact that our skin acts as a radiator. The more area of your skin is exposed, the more heat energy is lost.
- Conduction - When two objects are touching, heat will transfer from the warmer object to the cooler object. The rate of transfer is depends on the contact surface area and the temperature difference.
- Evaporation - When water evaporates it changes state from a liquid to a gas (also known as phase change). This process takes a lot of energy due to the strength of the hydrogen bonds in water.
- Convection - This is very similar to conduction but it also takes in to account how objects are moving relative to one another. An example of this is the Wind Chill Factor. The outside temperature may well be 0oC but if the wind is blowing at 30mph then the temperature felt on exposed skin may well be -10oC.
So if you are lying naked on stone up in the mountains when it is windy then you are going to get very cold very quickly.
How to reduce heat lossTo start with you should ensure that as much skin is not exposed to the environment as possible to reduce radiation energy loss. This not only means wearing clothes but also wearing gloves, socks and hats.
To reduce conduction loss you should ensure that a good insulator is placed between your body and the other surface. If you are to sit or lie on the ground then a foam mat or inflating mat is ideal. You want to buy as good a quality as possible so that it does not compress when weight is applied.
Evaporation can be drastically reduced by staying dry. Always wear synthetic thermal underwear base layers and mid layers that have a hydrophilic treatment applied to the fabric. This will actively transport perspiration away from the skin. Your outer layer should be waterproof to prevent water penetration in to your clothing layers but also allow the efficient removal of any water moisture from the body.
A good windproof outer shell will stop convection energy loss by preventing wind penetration in to your clothing layers, stripping it of any stored heat.
