Physics

Thermal conduction and insulation

In winter the ambient temperature is colder than the ideal temperature of the hands. Then, a heat exchange happens between the ambient air and your hands. From a point of view of your hands, it is a heat loss, and your hands cools down to below their ideal temperature (or heat gain from the ambient air's point of view). Therefore you feel your hands to be cold. That is physics, or in layman's term, commonsense.

Unfortunately it is rare during winter climbing you can change the ambient temperature, as you are exposed to the elements. However, you can and must somehow reduce the degree of heat loss from your hands as much as possible, if you want to keep them warm. How? That is another physics.

Heat loss (or strictly speaking, heat transfer) occurs in three forms: (thermal) conduction, convection, and radiation. As far as the hands are concerned, the latter two are usually negligible, and so we here consider only the conduction. Conduction is basically the transfer of heat from higher to lower-temperature sides. In physics, it is called the second law of thermodynamics, or is described as the entropy always increases, if you like a posh word rather than saying a commonsense.

The degree of thermal conduction greatly varies from material to material. A layer of material that has a lower degree of conduction is called insulation. The degree of insulation (inverse of that of conduction) is usually determined with the two factors: density and electric conductivity.

Metal has a high electric conductivity, and hence offers almost no insulation. If you hold a head of a metal iceaxe in winter, which you do and usually must during walking, your hand gets cold. I am sure you know it from both your experience and even instinct.

Most materials other than metal have very low electric conductivity, and so what matters is the density, namely, weight per unit volume. What is the material with the lowest density? Vacuum (aka no material). That is why vacuum flasks provide unbeatable insulation.

The second best, a long way better than the third, is air. Indeed, most of insulation layers humans use, be it clothes or for building, are essentially relying on air in principle (except for vacuum flasks). But air itself moves around freely and doesn't stay in one place long; therefore you need a container to keep air in a closed space.

Down does the best job for it, as it inflates naturally to keep the maximum amount of air per weight (while keeping the effect of convection minimum, to be precise). However, when it gets wet, its micro-fibres stick to one another, and the down quickly loses the loft, hence holds greatly less air per weight. That is why down provides very little insulation when wet. In winter, your gloves will get damp or wet eventually. For that reason, use of gloves of down is often a poor choice, unless the temperature is very low (which is unusual in Scotland).

So, it is no rocket-science you wrap your hands with a layer(s) of insulation, aka gloves, in winter or any cold environment, to keep the hands warm. In climbing, while you want a warm pair of gloves, you also desperately want a dexterity, as well as a gripping strength. Air, which offers the best insulation, has the least rigidness, and so inflated air-filled gloves don't perform well in climbing. You need to make an inevitable compromise somewhere in between.

Three additional factors to consider in the real world with conduction

Suppose you put on an insulation (gloves) around your hands, as you would. Now, apart from the materials of insulation, there are three important factors to consider for the application of conduction in the real world.

The first is potential gaps. Your glove may be thick in general, however, as far as I know, all the climbing gloves have a huge hole, that is, at a wrist part. You may sometimes see a part of a bare wrist end up being exposed, that is, there is no insulation at that part, from where the heat loss happens quite effectively. Even if a wrist is covered, some amount of the cold ambient air will come in, rob a heat off your hand and go out. To reduce the degree of heat loss and to maximise the amount of insulation around your wrist is one of the important points to keep your hands warm. I explain some practical measures later in this article.

The second is water or moisture. It is evil. Your wool gloves can be warm when dry, because it holds a decent amount of air between fibres (remember air is the best insulator on the earth). However, when it is wet, the air is replaced with liquid water, which is much heavier than air and so is much inferior insulator. Then, you will struggle to keep your hands warm.

More importantly, a part of liquid water evaporates, the process of which is accelerated due to your body heat and/or wind. When water evaporates, it takes off some heat, because the gas state (vapour) needs a higher energy than the liquid state.

For those reasons, it is vitally important to keep your insulation (gloves) as dry as possible to keep your hands warm. Again, the difficulties in winter climbing are,

1. your gloves and/or sleeves of your clothes inevitably touch, or even grip firmly, snow and ice, or even something wet but not frozen,
2. it may snow, or even rain particularly in Scotland, which will eventually find a way to sneak in your gloves,
3. your hands may sweat, making your gloves damp from inside.

The third is wind. It is a killer. Wind takes off heat in three forms.

1. An insulator is an insulator only when the temperature of the insulator is different (higher in the case of winter) from the ambient temperature. Gloves are warm because they hold air as an insulator with the temperature higher than the ambient temperature. However, unless the glove is windproof, air in (the fibres of) gloves is effectively and constantly replaced with air at the ambient temperature in windy conditions. Thus, strong wind makes non-windproof garments almost useless as an insulator.
2. Wind is a very effective accelerator to vapourise liquid water. Any garment, let alone bare skin, hold some moisture at best, or they may even be wet, during winter climbing. Strong wind would mercilessly rob heat off you via vapourisation of those water.
3. Even in the ideal conditions of wind-proof and dry garment, wind does take a heat off you. In general heat loss via conduction occurs more effectively when the temperature gradient (or difference between two materials) is larger. Wind accelerates the conditions. To visualise it, let's consider a lump of ambient air at -10 degC, sitting perfectly still next to your glove at +2 degC on the surface. The lump of air gains the temperature, say, by 9 degC to -1 degC after a certain amount of time via conduction, while your glove loses the temperature by 0.1 degC to +1.9 degC. By that time, the difference in the temperatures between the ambient and the surface of your gloves is marginal, and so the further heat-loss process is slowing down considerably. On the other hand, in windy conditions, the lump of ambient air at -10 degC is replaced continuously with another lump at -10 degC, and thus keeps the heat-loss process fresh.

Wind-resistant, or better wind-proof, materials mitigate the point 1, and point 2 to some extent, and so are highly recommended in windy conditions. Even so, the point 3 alone is effective. For that reason, many forecasts include the statement of feels-like temperature, which drops as the wind forecast increases.

Physiology

How come our hands are kept warm at the temperature of 30 degC ish even in an environment with a much lower ambient temperature with no glove? There is only one reason; our blood continuously delivers heat to the ever-cooling hands. Therefore, with no blood circulation, which happens when either a man or part of man's body organ is dead (a typical case for the latter is in a severe frost-byte), the temperature of hands will eventually drop to the level of the ambient temperature.

The temperature regulation of our hands (or any body part) is a competing process between heat-loss due to the lower ambient temperature and heat-gain due to blood circulation. Hence, you need to reduce the former effect, while enhancing the latter, to keep your hands warm in an cold environment. Physics determines the former, as explained. Physiology determines the latter.

The amount of blood a hand receives is a function of the heart rate and the size of blood vessels in the arm and hand. Higher the heart rate is, and larger the size of blood vessels is, warmer your hand will be.

Psychology

Climbing is all in your head

said a friend of mine.

I think it is common people are surprised to find how much they could do when they thought they couldn't but anyway pressed on and tried hard. Such a moment is a beauty of life, be it in climbing or whatever.

However, when your hands have become numb and don't do the job which they are expected to do, I don't think a macho attitude of bite a bullet and just get on with it works well, because your hands are already out of your control.

My suggestion is, experiment, learn, and know yourself (your hands) and your limit, act intelligently, be attentive to your hands and look after them really well without negligence or being lazy, and keep a fine balance between reckless and conservative.

Keep the core warm

1. When you feel cold with your whole body, you have no chance to have warm hands, as mentioned. So, first and foremost, keep your core warm! In terms of the priority, cover up well and protect head, neck, armpits, upper chest, and groin. As they say, put on a warm hat first!
2. Protect your wrists particularly well. The artery runs close to the surface of the skin at wrists (that is why wrist-cut is a common method to commit suicide), and therefore the wrists are susceptible to the ambient temperature. And of course, the artery is what pumps up the heat to your hands.
3. Keep your body as dry as possible, both from outside like snow/rain and inside (sweat). It is easy to say, hard to achieve, for climbing is a stop-and-go activity. Experiment various ways, and find the ones which suit you.
4. Feed and hydrate yourself well.
5. Get fit!

Get the right equipment and spares

1. Don't be stingy with gloves and related equipment. Invest for them. Be open-minded and try many different models for not only climbing but also other fields like biking, skiing, and even industry, and find the models that work for you. Note that for gloves, what you pay is not always what you get. If a pair does not fit you, it is useless, for example.
2. Gloves do get wet, no matter how careful you are. Take spares.
3. Take a few pairs, depending on your use. I usually take 5-6 pairs for day's climbing. For Scottish climbing, the following is my standard (though it varies, depending on the route, conditions etc):
   • ultra-thin waterproof (walk-in/out, gear-up)
   • dextrous pair × 2-3 (for crux pitches)
   • waterproof warmer full-finger (for less technical ground when cold)
   • mitten (for cold belay)
   • waterproof over-mitten (which can be worn over any of the above)
4. Take a pair of mittens. They are far warmer than gloves with full-finger.
5. Non-windproof gloves would be useless in windy conditions as an outer layer.
6. In Scotland, waterproofness is desirable, though not essential for technical climbing pitches.
7. Make sure your wrists are fully covered by clothes and/or gloves and no part is exposed. If it does, give up having a warm hand.
8. Thumb-loops in your base-layer (or middle layer) are very useful. Alternatively wrist-bands/gaiters (like one from Marmot) do a (maybe even better) job, though a little bulkier.
9. Consider the alternative sleeve layering system, that is, each layer of glove and clothes covers the wrist part alternatively. For example, the crux of a thumb is covered with a thumb-loop of your base-layer, an inner glove is worn over it, the wrist-hem of the inner-glove is covered with a mid-layer clothes, and its wrist part is covered with an over-glove, which is covered with a shell-jacket. It is awkward to arrange, but once you have done, you will appreciate its warmth and protection.
10. Make sure the hem of each glove is tightened well (but not to the extent to restrict the blood flow). That would keep the wind and snow out. Some mittens are equipped with an extra-long sleeves (like one in the figure in the beginning of this article) and they are helpful in that respect.
11. Which of jacket and outer glove should come at the top? When you expect your hands to keep pointing mostly downwards, such as walk-in, the jacket should come at the top. When you expect your hands to keep pointing mostly upwards, such as steep climbing, it should be the opposite. In short, the set-up should block snow or rain at the outermost layer.

In approach and walking

1. Your hands sweat and so your gloves become damp. Don't use your pair of gloves for crux pitches in approach, and save it.
2. Windproofness (or waterproofness in Scotland) is handy, or essential if windy. Without that, especially in gusty conditions, your hands would become too hot (and sweat) when still, and too cold when a gust blows.
3. Don't let your hands become too cold. Take care of them well. Otherwise, you will have a trouble in gearing up, and your hands may stay cold all day.
4. Be ready to adjust the glove system during your approach. In Scotland, the gloves you need when you set off the sea-level may well be different from what you want near the end of the approach high up, cold and windy.
5. You don't have to expose always your hand(s) (in gloves) to winds. You can tuck it away under your sleeve, providing your gloves are not bulky. Or, you can place it in the lee side of your body, or between your back and rucksack etc. Every little helps.
6. Keep your sack light if possible. Change the position of shoulder straps at times, as they restrict the blood flows to your arms and hence can make hands cold.
7. If you use a walking pole(s), expect your hands will become colder than otherwise, and so dress appropriately. It is because your hands are kept higher than dangling along the sides of your body, which hinders a smooth blood flow to your hands. Also, the hands are kept exposed to the wind.
8. In windy conditions, consider taking one walking-pole only as opposed to a pair. If you take a single pole only, you can keep the free hand warmer and can alternate the hands to keep both hands reasonably warm.

In gearing up

1. Make yourself warm, putting on a warm jacket etc. That will keep your hands warm(er) and dextrous for the jobs you need.
2. Dextrous windproof gloves are the most handy.
3. I have once witnessed a friend of mine gear up from harness to crampons with mittens on — it seemed a very handy skill to have on a windy day!

Climbing

1. Use a thin pair of gloves while actually climbing. Full stop.
   1. Thick gloves make you tired a lot faster particularly on steep grounds, because you need a lot more strength to keep hold on axes, and therefore they make climbing harder, and accordingly result in more chance of a fall or failure.
   2. Thick gloves are cumbersome, and so you tend to overgrip. Then, paradoxically, they often make your hands colder than thin gloves.
   3. Everything takes time with thick and cumbersome gloves, which makes you slower, more tired, colder, more frustrated, and consequently climbing becomes more risky and less fun than otherwise.
2. You deal with snow, ice, and maybe wet rock/turf etc. No matter how waterproof the gloves are, they become wet after pitches of climbing. Take spares. Thin gloves don't weigh much, and can be stowed away even in the pockets of your jacket.
3. For general-use gloves, you would want a tiny bit of space at the tip of each finger to keep the hand warmer. For climbing, no space is far better, as any extra slack in gloves catches gear etc all over.
4. Go leashless (with leashless tools, and perhaps use security-lanyard instead). Leashes restrict blood flow at the wrists, force you to keep the hands high all the time, make the gear handling awkward — thus, everything is the recipe to make your hands cold!
5. Shake or even windmill your arms occasionally, when you can, to help enhance the blood flow.
6. Try to avoid overgripping and stay relaxed.
7. Modern technical axes are a great help to keep the hands warm, because
   1. your hands usually stay clear of ice, snow, or rock,
   2. the angle to hold the axe is physiologically far more natural than classical axes, and so it helps keep a better blood flow,
   3. climbing would feel easier (on steep terrains), and so you progress faster and more relaxed, which keeps you and your hands warm,
   4. in steep terrains, hanging elbow-hook rest is a useful skill to learn.

Belaying

1. Once you (have lead a route and) have reached a belay, and are ready to belay your partner(s), don't expect you can keep using your climbing gloves in belaying duty (though obviously you can if you feel warm enough; mind you, to handle snow-covered ropes for the entire length would make your gloves wetter). Put on warmer gloves, maybe mittens.
2. A possible way is to put on over-gloves (mittens) over the climbing gloves you have just used, which would save a time to change gloves, though it may not be warm enough. Of course, the over-gloves must be waterproof inside for that purpose.
3. If you change your climbing gloves and intend to keep using your climbing gloves for the next and/or later pitch(es), it is recommended to keep them inside a pocket of your jacket to keep them bearably warm. For that purpose, the pocket of your jacket must be waterproof inside.

General

1. It is recommended to put a security bungee cord in each glove, which is fixed to your arm, so that you would not lose the glove. The length of the bungee cord must be carefully adjusted so it would not interfere with climbing or gear. Downside of this method is when a glove dangles off your arm, it does so up-side down and may (or will) collect snow etc inside the glove. Some gloves are equipped with a tiny draw cord on a ring finger so you can hang the glove in the better orientation.
2. Keep your next pair (the pair you plan to use next) warm, perhaps keeping them in a pocket. If you keep a right-hand and left-hand gloves in a right and left pockets, respectively, it will save you from a potential faff to work out which glove is for the right (or left) hand.
3. Once your hand has become too cold, the quickest way (on a hill) to warm up is shove it in your either groin or armpit, preferably directly on the skin, and apply a warm pressure on it. I am not sure if your climbing partner wants to shake hands with you after that, but no worries, by the time the team has completed the route, your mate has likely forgotten it!
4. Another handy way to warm up a hand is to fist your hand inside your glove (aka, do Doraemon, as Japanese calls), maybe wrapping your thumb with the other 4 fingers. Make sure the hand is bare, namely, it should be fisted inside the innermost glove, or otherwise it is far less effective, however thin the innermost glove is.
5. Meshed liner-gloves (like the ones sold by the Japanese manufacturer Finetrack) are useful to deal with sweaty hands. However, you would struggle to fist your hand inside the liner glove, and so that method to warm up a hand is not effective with them.
6. Don't warm up your hand with your breath (unless your glove is already wet). It may work for a second, but then the added moisture will make it even colder soon.
7. Portable heat packets may help. However, for the purpose of reviving the warmth of your hand, they give little help — the two ways explained above are far more effective and immediate treatments. I guess if you keep a packet inside your glove, that will be a significant help in keeping your hand warm.
8. Battery-powered mittens are commercially available. They must be a bliss in cold belays.
9. Keep your hands protected from wind all the time, if practical, such as, keeping it in the lee side of your body or behind a rock. The best way is to unfold a group shelter and get in. You will be amazed how warm it is. Having naturally cold hands, I sometimes gear up inside a group shelter on windy days.
10. If you feel your hands to be cold, or preferably before that moment, do something about it by all means! It is surprising to see many people do nothing while complaining how cold their hands are. Some example measures are described above in this subsection. Every little helps, seriously.
11. [Added on 2016-04-06] Here are some suggestions for how to store your next spare gloves:
    1. In a (preferably waterproof-lining) pocket(s) of your jacket or trousers
    2. Next to your warm water bottle (providing there is absolutely no leak)
    3. With an activated heatpack in it
    4. Next to your back in the rucksack, providing you carry the sack on your back all the time.
    Note shell-gloves like over-mittens do not have to be stored in warm places, or actually they had better not be in a cold environment, where the surface temperature of inner gloves is below freezing, because a shell at above-freezing temperature put over an inner glove will melt the snow on the inner glove, and will make it damp.
12. [Added on 2016-04-06] Eliminate the necessity of bare hands on the hill. Such as, complicated packaging for your lunch/food is undesirable. If a fastener of clothes or bag is too fiddly in its original design, put a little draw-cord or tab on it (make sure it would not be caught while climbing). Take a stylus pen for your smartphone. Choose and take more glove-friendly gear — is your camera easy to operate with gloves on, for example?
13. [Added on 2016-04-06] Be fussy about snow on your gloves and jacket. As long as snow stays as snow, it does not do much harm. However as soon as it melts, it does. Dust away frequently snowdust on your gloves and on sleeves of your jacket.