See in documentaries and feature films the inhabitants of the desert, wrapped from head to toe in thick fabric. At the same time, outwardly they are quite comfortable and not hot. Usually they also drink hot tea, which also does not correspond with our idea of correct and comfortable behavior in the heat.
The thing is that the dense retains life-giving moisture on the skin, preventing it from drying out; the body's secretion is then stored inside a robe or other warm clothing, without going anywhere. In addition, such clothing protects against heat stroke by preventing the human body from coming into contact with hot air. In fact, warm clothes in hot weather act as an additional thermoregulatory agent.
A thick robe and (for example, Uzbek) keep the pressure, pulse and temperature of its owner at normal levels. In fact, the only thing in this robe is to drink enough fluid so that your body has enough of it. Hot tea is preferable because it stimulates sweating, which cools the body.
Should you wear more clothes in summer?
As for the usual lightweight clothing, its main disadvantage can be considered the lack of protection for the skin. In such a situation, the skin dries out, does not cool down naturally through sweating, and the hot air has a negative effect on the human body. If you are not careful enough, it is easy to get sunburned, get sunburned, or even get heatstroke in light clothes. And if you additionally block the sweat glands with deodorant, so that the body simply does not have the opportunity to produce it traditional way and cool the surface of the skin, getting rid of excess heat, nothing good will come from wearing overly open clothes.Linen has the ability to stay cool even under the hottest rays of the sun, so you simply cannot find a better fabric for summer clothing. But we must take into account that linen wrinkles very much.
If you wear revealing clothes and drink ice water, your body is in conflict with the surrounding space. The vascular response to such actions may be inadequate, which may result in general discomfort. In addition, it is very easy to catch a cold after drinking too much cold water on a hot day.
Don't wear clothes in summer dark colors. It heats up too quickly in the sun.
Of course, it is not necessary to wrap yourself in robes, which, despite their benefits, can hardly be called fashionable clothes, but you can change miniskirts and T-shirts to long linen or cotton dresses and skirts, change sweat-blocking products to those that remove bad smell. In such equipment it is much easier to cope with the terrifying heat.
How are warm clothes different from cold ones? What or who keeps us warm in a fur coat, padded jacket or down jacket? In this article we will talk about why clothes"warms" how she does it, and whether warm clothes always meet our expectations
The agony of choice
When choosing clothes, shoes, underwear or hats, we almost always try to evaluate how warm the item is. Sometimes, for example, when choosing a summer shirt, such an assessment occurs almost imperceptibly and is unlikely to have a strong influence on the purchase. But often the ability of clothes to warm comes to the fore, and then we devote a lot of time to this issue. After all, we need to make sure that we don’t freeze when we climb Mount Everest or try to bike to the North Pole.
We meticulously examine clothes, evaluate their texture, thickness and density, look at the reverse side, feel and wrinkle to understand what is inside. What are we looking for when performing these almost shamanic manipulations? Are there really secret heat sources that, like a good Samaritan, will save us in bad weather? Of course, most of us, when choosing clothes for the city, may not think about it at all. What difference does it make why clothes are warm? It's warm and ok. If it’s cold, we’ll wear something else.
But the situation changes when you need to choose clothes for a hike, expedition, climbing or long journey. In this case right choice equipment becomes task number one, because we can’t take with us too many camel blankets, grandma’s socks, sheepskin coats and Chaliapin fur coats. They, of course, are guaranteed to keep us warm in any weather, if not separately, then together, but how many Sherpas do we need to hire so that they can at least lower all this cargo in the elevator before we drag it into the mountains?
Warm yourself
Of course, few of us really think that heating clothing itself warms, unless, of course, we are talking about rather exotic types of electrically heated equipment.
The source of heat of the human body is the body itself, and the task of warm clothing is to passively retain this heat next to the body. Or, in other words, the role of warm clothing is to slow down the heat exchange between the human body and the environment in order to eliminate excessive heat loss and prevent hypothermia.
A freezing person is one whose body too actively shares its heat with the environment.
For an ordinary person who has homeostasis, that is, the ability to maintain body temperature unchanged with minor temperature fluctuations environment, - the normal temperature range of this environment is from 27 to 32 °C. That is, both hypothermia and overheating are equally bad for a person.
The source of heat of the human body is the body itself, and the task of warm clothing is to passively retain this heat next to the body
Note that if the body temperature normally fluctuates slightly around thirty-six and six, known from childhood, then the ambient temperature is a continuous act of creative unpredictability of Jupiters, Poseidons and other Quetzalcoatls. Therefore, clothing suitable for all climatic conditions does not exist, unless, of course, you are a steppe nomad, fleeing both the cold and the sun from the same fur hat— we malachai. Yes, it turns out that you can also escape the heat with the help of warm clothes. After all, if a fur coat slows down the outflow of heat from the body, then it does the same with heat that tends to penetrate in the opposite direction - from an excessively heated environment to the human body. The same job is done by a funny felt bucket hat, which, along with a birch broom, is one of the most important pieces of equipment for a sauna lover.
An important fact follows from all this: no clothing should completely block the body’s heat exchange with the environment. Otherwise, it will become like an impenetrable space suit, to which a special air conditioner is connected to maintain a normal microclimate. The unfortunate cosmonaut is forced to drag this box of hoses with him everywhere until he gets into the rocket to accomplish the feat. But we haven’t yet accomplished feats on a cosmic scale, so we’re unlikely to take a household air conditioner with us on the climb.
So, clothing, no matter how warm it is, must, on the one hand, prevent excessive heat outflow from the body, and on the other hand, still allow this outflow to occur in controlled volumes to avoid overheating.
This is usually solved in a complex manner. Firstly, the basic selection of clothing suitable for the intended conditions of its use is essential. Secondly, such clothing should be modifiable if possible, that is, it should allow the use of additional insulating layers or underlays. Thirdly, such clothing should have effective means ventilation: unfastening valves, special ventilation holes, breathable materials, etc. All this is necessary in order to expand the temperature range at which this type of clothing would provide a person with comfortable conditions.
A freezing person is one whose body too actively shares its heat with the environment
A little physics for lyricists
But let's return to the question that we formulated at the beginning: how do warm clothes warm? The answer to this is given by physics, or more precisely one of its branches - thermodynamics - which studies, in particular, the processes of heat transfer from one body to another. Since in this article we are considering the principles of operation of insulation, we are not interested in the general case of heat transfer from a more heated to a less heated body, but in the special case of heat transfer from the human body to an environment that has a significantly lower temperature.
Physics says - and we won't argue with it - that there are three main ways of heat transfer. Two of them - thermal conductivity and convection - are carried out through direct or indirect contact of bodies participating in heat exchange, and one - thermal radiation - uses electromagnetic waves to transfer heat.
In practice it looks like this. Direct contact of a warm body with a cold one leads to the fact that the molecules of a more heated body transfer their energy to the molecules of a less heated body directly, through direct interaction. This, for example, happens when we take a cold stone or piece of ice with our bare hand. The molecules of the warmer body, that is, the hands, transfer their energy to the less “energetic” ice molecules until their temperature is equal. In this case, the ice will only melt slightly, but your hand will have a hard time. Many probably know a cruel children's joke about a tongue and a metal handrail in the cold: it is enough to just touch the strongly cooled metal with your tongue for a moment, and the moisture contained on the tongue will transfer its heat to the piece of iron, cool down, freeze and freeze in a terribly tragic, funny and absurd way tongue to some object in the middle of a snowy yard - a horizontal bar or a swing.
Heat transfer during direct contact of bodies with different temperatures
Indirect contact assumes that between the bodies involved in heat transfer there is an intermediary - water, air or another more or less dense medium through which the transfer occurs. In this case, the molecules of a hotter body first come into contact with the molecules of the mediator and transfer part of their energy to them. Then"hot" the molecules of the mediator reach the surface of the less heated body and share with its molecules the energy received from the first body. In other words, mediator molecules transfer heat by moving from one body to another.
The rate of heat transfer depends on the material of the mediator’s body and is calledthermal conductivity.The higher the thermal conductivity of a material, the faster it heats up and cools down and the more efficiently it transports heat.
Warm clothing is clothing that creates a zone with a low thermal conductivity coefficient between the surface of the human body and the environment
Warm clothing is required to slow down the flow of heat from the human body into the environment. To do this, two conditions must be met:
- Eliminate direct contact of the surface of human skin with the environment by introducing an intermediary - clothing;
- Select an intermediary (clothing) with a thermal conductivity coefficient K that would ensure the maintenance of a comfortable temperature level of the body at a certain temperature difference between the human body and the environment.
Thus, the transfer of heat from a more heated body to a less heated one through an intermediary is slower, the fewer molecules of the intermediary are involved in the transfer of energy. In other words, the warmer a person is, the lower the thermal conductivity coefficient K intermediary. Given this, it can be assumed that the warmest intermediary clothing is a vacuum, that is, an environment in which there are no molecules that transfer heat.
Here’s a funny conclusion: the warmest clothing is its complete absence, a layer of complete molecular emptiness, vacuum, between the human body and the environment. The inventor who discovers a way to hold a small layer of vacuum around a living and active person will probably receive a Nobel Prize, but so far nothing more suitable than an ordinary thermos has been invented in this area. It is as difficult to imagine climbing Mont Blanc in a thermos as storming Everest with air conditioning, so until the Nobel version appears, more sober solutions to this problem will have to be considered.
So, warm clothing is clothing that creates a zone with a low thermal conductivity coefficient between the surface of the human body and the environment.
We already know that the lowestK has a vacuum - an environment that practically does not contain particles of any substance. The thermal conductivity coefficient of vacuum is zero. The only type of heat transfer possible in a vacuum is electromagnetic radiation. That is why thermos flasks are made mirrored. The mirror coating reflects radiation, and heat transfer inside the vacuum zone of the thermos becomes even less intense. But since we can’t put a thermos on ourselves yet, we can only consider other options.
Physics says it's pretty lowK possesses air. Unlike a vacuum with almost zeroK , the air has K = 0.026 W/(m K) . This means that air is a poor conductor of heat. If an air layer of sufficient thickness is placed between the human body and the environment, then we will get one of the warmest clothes, not counting, of course, a thermos. In this case, such an air gap must be in a closed volume so that its air does not mix with the cold air of the environment. It is even better if there are several such closed volumes so that the air inside the layer does not mix.
In truth, imagine clothes in the form hot air balloon, somehow miraculously tailored to a person’s figure, is not much simpler than a zip-up thermos. Air does not have mechanical strength, so there must be something else in the air gap, some material that, on the one hand, will create and maintain the spatial structure of the gap, prevent the mixing of the air contained in it, and on the other hand, will not significantly influence heat transfer due to its ownK , that is, it will not create so-called “cold bridges”.
Such materials are known. Today the leader in heat retention, that is, the material with the lowest K , counts . Its meaning K =0.008 W/(m K) - and this is even less than that of air. For comparison: wool, previously widely used as insulation, has K = 0.055 W/(m K), this is almost seven times higher than that of eider down.
Of course, such extreme valuesK are required mainly for equipment used in equally extreme conditions. Under normal circumstances, sufficiently warm clothing will be those thatK filler is not much different fromK air, and there are a lot of such materials - from artificial insulation to the usual feather-down mixture used in most down products. MagnitudeK for all these materials lies in the approximate range from 0.024 to 0.039 W/( m·K), so they are all suitable for making warm clothing.
Today, eider down is considered the leader in heat retention, that is, the material with the lowest thermal conductivity coefficient.
If we pay attention to what materials humanity has used historically to preserve heat, then with all their diversity - from animal wool to modern synthetic materials and even aerogels - it turns out that their main property is the ability to bind and hold in place the volumes of air they contain, while maintaining structural integrity. We evaluate this ability by carefully feeling the clothes before purchasing. Fur pile fur coats, thick woolen sweaters, elastic down jacket rolls or sandwiches synthetic insulation— everything is analyzed for its ability to retain warm air from the beloved organism.
In addition, in order for warm clothing to retain its heating characteristics, it is necessary to ensure such operating conditions that do not radically changeTO insulating filler. For example, it is not recommended to allow the insulation to become wet, since water, firstly, hasTO = 0.6 W/( m K), which is tens of times higherTO air, and secondly, it can change the spatial structure of the insulation. Modern insulation materials retain their structure when moistened, but in the case of down, its getting wet and sticking together leads to the fact that a wet down sleeping bag or jacket that has become useless is easier to forget for a while than trying to dry it in camping conditions.
Summary
Warm clothes warm a person with his own warmth.
The lower the thermal conductivity of the insulationTO , the warmer the clothes, all other things being equal. The best insulation for this indicator is eider down.
Clothing with effective insulation requires an equally effective ventilation system to prevent overheating.
Wetting insulation, especially insulation based on natural down, should be avoided.
“I want to become Vim Hove!” - I said. MCH felt my forehead. I had to explain: “He is known as the Iceman, he easily plunges into a container of ice, and climbs Mont Blanc in only shorts!” The beloved sighed: “Khovom, so Hovom.” Just don’t forget to put on socks and a scarf, otherwise you’ll catch a cold again!”
The first commandment of a cold person: don’t take a step out of the house without eating oatmeal! Or buckwheat. Or anything else. Food is energy, and most of it (up to 75%) will be used to warm up your loved one. By the way, in the cold season you can eat 400 calories more per day.
The second commandment: vegetables are good, but chicken and lamb are no less needed in winter. If you continue to eat as if it were summer, you could end up with chronic fatigue syndrome. And if you often feel cold, switch to “hot” foods: meat, fish, nuts, potatoes, cheese, pumpkin, dried apricots, bananas, grapes. Onions and horseradish also help, but this is not for everybody. And, most importantly, don’t forget about the spices: ginger, cinnamon, curry, pepper, cumin and garlic - they warm you up almost instantly.
2. Watch the temperature (of the drink)
There was this Soviet poster: a guy in a jacket waves his hand away from an extended glass of vodka. It's time to hang it on the wall. The fact is that alcohol in the cold can only warm you up for a short time, and after that the body will rapidly begin to lose heat. By the way, the coffee doesn’t heat up either. It is better to drink herbal tea, tea with ginger or lemongrass, as well as hot chocolate (the favorite drink of many climbers). Also, take note of this recipe: add half a teaspoon of cinnamon to a glass of apple juice. Bring to a boil and drink.
3. Develop tummo
Tibetan monks are able to dry wet towels on their naked bodies on a winter night. They are proficient in the practice of tummo. It is based on a visualization method: sitting on the snow, a monk imagines how a flame the size of a hair arises in his body, it flares up and begins to fill the body. Finally, the inner heat bursts out. This is not just a legend. The effectiveness of tummo has been proven by researchers.
4. Massage your arms and legs
Do you know when the thought of cold appears? When your hands or feet freeze. To quickly save your limbs from the cold, massage them. If you have some time, arrange an aromatherapy session: add to any foot or hand cream essential oils- 4 drops of sage, 3 drops of fennel and 2 drops of ginger. The oils will cause a quick surge of heat and envelop the body with aroma. You can do a massage before going outside and upon returning to the warmth. Another recipe: rub a drop of thyme or clove oil into the crook of your elbow. It will get warmer.
5. Breathe correctly
“Our lungs can warm us!” — biophysicist Karl Trincher suggested half a century ago. His enthusiastic followers found out that in winter you need to inhale slowly and not very deeply, this calms the nervous system and allows you to quickly adapt to the cold. If you feel that “five more minutes and I’ll completely freeze,” use the method of the already mentioned monks: inhale through both nostrils, and exhale through one, holding the other.
6. Follow the latest news (science)
USB gloves were developed specifically for office frostbites. Looks ordinary knitted gloves without fingers, but a wire with a connector comes out of them, like a flash drive. You connect it to the computer, and after five minutes the gloves heat up to 46 degrees! By the way, there are USB slippers of a similar design. Microwave heating pad(Cozy Cuddles) looks like soft toy. After two minutes in the microwave, it retains heat for hours and shares it with its owner. Thermal pack is an option for long walks. Put it in your jacket for extra warmth.
7. Forget about loneliness
Scientists have found that a person who feels lonely freezes faster. There is also an inverse relationship: if you look at a photo of your loved one, imagine your family or bosom friend, you will immediately feel a surge of warmth. Even more effective is hugs. We are warm-blooded and produce heat. Snuggle up to your loved one more often.
8. Toughen up , it saves
I am not advocating jumping into an ice hole. You can also harden yourself at home. Place a wet towel in the freezer for half an hour, then stomp on it for a few minutes. After the procedure, immediately put on warm socks. If you do this every night, your feet will get used to it and become less sensitive to the cold.
9. Try not to be nervous
Stress affects our body in the same way as frost. During severe emotional shock, blood drains from the limbs and “hurries” to the brain so that the person can make the right decision. When cold and stress meet, the chance of freezing increases! Learn to relax. An exercise like this would work: a short time tense all your muscles and then suddenly relax them.
10. As a last resort
Rumor has it that actors, in order to avoid freezing during winter filming, stick mustard plaster on their shoulders. Blood quickly rushes to the surface of the skin and gives a feeling of warmth. Alternatively, you can rub your legs with anti-cellulite cream with cayenne pepper. Same effect. Vodka works just as well as pepper. Another “insulation” is paper. If you have to stand outside for a long time, put paper insoles in your shoes. It will become easier.
PS. Thermal underwear also helps a lot. Tested and effective.