According to statistics, from 10 to 15% of people who died on tourist routes were victims of overcooling. Cold threatens humans most in high-latitude zones. In the ice zone, tundra, forest-tundra, in winter time in the taiga, steppes and adjacent semi-deserts, in the highlands.
Cold as a risk factor in an emergency and in an autonomous existence.
But these zones are also heterogeneous in temperature characteristics. Even in the same area, at the same time, the readings of the thermometer can vary by a dozen or more degrees. For example, often in river valleys, gorges, and other hollows, lowering the temperature as a result of the flow of cold air into the lowlands is much more noticeable than at elevated points of the relief. A lot of humidity means. For example, in the region of Oymyakon, which is the pole of the cold of the Northern Hemisphere, temperatures can reach minus 70 degrees, but due to the dryness of the air, they are easily transported.
– thickets, folds of relief, low air temperatures, coupled with strong winds, can reduce a person’s survival time to several hours.
The effect of clothing on heat and cold protection.
Long-term survival at sub-zero temperatures depends, in addition to the climatic factors listed above, on the state of clothing and shoes at the time of the accident, the quality of the shelter built, the availability of fuel and food, the moral and physical condition of a person. In an emergency, clothing is usually able to protect a person from cold damage, frostbite, general hypothermia, only for a short time, sufficient to build a snow shelter.
The heat-shielding properties of clothes depend primarily on the type of fabric. It keeps the cold best and keeps the finely porous fabric warm. In this case, a direct dependence of thermal conductivity on the number of pores is noted. The more microscopic air “bubbles” enclosed between the fibers of the tissue, the closer they are to each other, the less such tissue passes heat from the inside, and cold outside. That is, the more “leaky” clothes, the better it warms – this is such an interesting paradox. A lot of air pores in woolen fabrics. In soft wool fabric, their total volume reaches 92.3%. For comparison: in more “cold”, smooth flaxseeds, it does not exceed 48.8%.
By the way, the heat-shielding properties of fur clothing are explained by the same effect of air pores. Each villus of fur is like a small hollow cylinder with an air bubble sealed inside it. Hundreds of thousands of such elastic micro-cones make up a warm fur coat. For greater clarity, the following figures characterizing the heat-shielding properties of the fabric can be given. If we take the thermal conductivity of air per unit, then the thermal conductivity of wool will be 6.1, silk – 19.2, and linen and cotton fabric – 29.9.
Recently, clothing made of synthetic materials and fillers has been widely used. Here, air capsules are enclosed in the thinnest shell of artificial fibers. It is possible that synthetic clothing loses a little in comparison with fur in warmth, but it has a number of other indisputable advantages. It is very light, does not impede movement, properly stitched and fitted, almost not felt on the body – you go, as in a summer shirt.
In addition, synthetic fabrics are almost not blown by the wind, snow does not stick at all, they get wet a little, even immersed for a short time in water, and, very importantly, dry quickly. And their price is ten orders of magnitude lower than some simple quilted jackets made of natural sable. True, synthetic clothing contributes to increased sweating during intense physical work, but this trouble can also be avoided if modern “breathing” fabrics are used as covering materials, that is, those that “remove” excess moisture while retaining heat.
Probably, in this case, you should not save energy on finding the right fabric and money for its acquisition. It’s more profitable to buy what’s better. To yourself did not work out more. Well, if it was not possible to sew similar clothes from new-fashioned materials, you can always adjust the internal temperature regime, partially undressing, before preparing firewood or overcoming a section of difficult terrain. Perhaps one of the best options is to use multi-layer clothing from different fabrics. Special studies have shown that 4-5 layers of clothing retain heat best.
For example, a thick cotton suit, several thin, not very tight-fitting woolen pants and sweaters (2-3 thin sweaters warm much better than one thick one, since an air gap forms between them) and a suit or jumpsuit made of synthetic fabric. But this is a matter of taste. I think that the native of the North will not agree to exchange his worn deer park for even the most high-tech synthetic jumpsuit. And he will be right. It’s better to survive in what you’re used to living.
The effect of shoes on heat preservation and cold protection.
Shoes play a very important role in winter emergency conditions. Suffice it to say that 90% of all frostbite falls on the lower limbs. Therefore, a person who crashes in the winter time, first of all, should pay attention to the condition of his legs. By all available means, one must strive to keep shoes, socks, footcloths dry. To do this, you can make shoe covers from improvised material, wrap a piece of loose fabric around your legs, and so on..
All the material left after this can be used to warm clothes, protect your face from the wind. But, I repeat again, clothes, no matter how warm they are, can protect a person from the cold only for a very short period of time – hours, rarely days. And if you do not use this time properly – to build a warm shelter, in search of the nearest settlement, no clothes will save a person from death.
Properties of shelters, their ability to protect from the cold.
Very often in an emergency, people prefer to set up fabric tents, build shelters from the wreckage of a vehicle, logs. They cling to traditional materials – wood, metal – as salvation. They seem to them much more reliable than, for example, snow. Meanwhile, this is a mistake for which one often has to pay with one’s own life! When building shelters from traditional materials, it is practically impossible to achieve a tight seal of joints and joints of building boards.
Shelters are blown through by the wind. Warm air escapes, and cold penetrates through numerous gaps, so in the absence of stoves, stoves and the like, highly efficient heating devices, the temperature in the shelter is almost always the outside. In addition, the construction of such shelters is very time-consuming, often associated with the risk of increased injuries. There are frequent cases when such an impromptu shelter collapses due to wind pressure or due to careless movement and puts the group in critical conditions.
Meanwhile, excellent building material is literally under the feet of a person. This is the most ordinary snow. Due to the porous structure, snow has good thermal insulation properties. It is easy to process. Snow shelters – igloos, caves, houses, lairs, erected in one and a half to two hours, reliably protect a person from exposure to low temperatures and wind, and in the presence of fuel provide thermal comfort. In a properly constructed snow shelter, the air temperature only due to the heat generated by a person rises to minus 5-10 with a 30-40-degree frost outside.
With the help of a candle, the temperature in the shelter can be raised from 0 to plus 4-5 or more. Many polar researchers, having installed a pair of stoves inside, heated the air to plus 30. Thus, the temperature difference inside the shelter and outside can reach 70 degrees, and without the use of heat-emitting devices – 30-40 degrees! But the main advantage of snow shelters is the simplicity of construction. Most snow shelters can be built by anyone who has never held a snow shovel or snow knife in their hands..
The effect of nutrition on cold protection.
The availability of food supplies is crucial for the long-term survival of the snowy shelter built and for maintaining active life. A decrease in the ambient temperature even by a degree noticeably stimulates the metabolic processes in the body. Received food begins to burn intensively, releasing significant amounts of thermal calories. At the same time, the body receiving cold begins to save internal heat in every possible way..
The vessels on the surface of the skin are narrowed, the respiratory rate and the number of heart beats per minute are reduced, that is, the process is inverse to the overheating of the body. If during the heat it is important to get rid of excess heat calories, then in the cold they must be kept inside. The term resistance to low temperatures to a large extent depends on the mental state of a person. For example, a feeling of fear many times reduces a person’s survival period even at near-zero temperatures. Panic fear of freezing speeds up freezing.
And, on the contrary, the psychological attitude – “I am not afraid of the cold. I have real opportunities to protect myself from its effects ”- significantly increases the survival period, allows you to intelligently distribute time and energy, introduce the planning element into your actions. The most important commandment in martial arts with the cold – TIME TO STOP. It is impossible to overcome the cold with one psychic force. In such cases, it is better to play it safe, turn back a little earlier, set up camp, build a shelter, relax and so on. A little earlier – it’s still better than a little later. It sometimes saves a life!
Based on materials from the School of Survival in Natural Conditions.