Hazards: Cold. Of wind double-dipping, clothes into water single-dipping et al.

[vicky_molokh]

Greetings, all!

I'm curious about the various nuances of cold hazards.

Fast wind forces HT checks to occur every 15 or 10 minutes instead of every 30. However, fast winds also reduce the effective temperature, which adds penalties to the HT roll. I don't get it. This looks suspiciously like double dipping. I thought that effective temperature from wind chill already includes the nastier cooling in such weathers. But it seems that as-is, -30°F real temperature at zero wind is better than -30°F effective temperature with fast wind (i.e. when the temperature is much higher, but counts as -30°F after adjustment for wind). What gives?

Cold checks start at 35°F and below. Winter clothes provide +0 to those checks, no or light clothes provide -5 to them. What's the point of 'normal' clothing as far as staying warm goes? It doesn't seem to serve any niche game-mechanically.

Wet clothing gives an additional -5 to HT checks to resist cold, which is as bad as no clothing (apparently except in the case of arctic clothing, which has an inherent +5, resulting in +0 . . . I don't think it makes sense, but maybe I'm wrong). Anyway, I did once hear in some natgeo-clone show that getting out of wet clothes is a #1 priority but . . . is it really better to strip naked after climbing onto the shore from under the ice? It seems rather dubious to me, but I know next to nothing about outdoor survival. (Yes, I do realise that getting a fire-and-shelter is a priority; I am also asking these questions on the assumption that the adventurer has the sorts of stats and/or situation that these events aren't an immediate death sentence, but still a serious threat to life and limb.)

I don't quite get frostbite: High-Tech says it's for exposed locations, but (a) wikipedia seems to say it's about mostly about reduced peripheral blood flow instead and (b) the wording in the textbox is such that I don't get when an exposed location should or shouldn't suffer frostbite damage along with FP damage.

"Recovery of FP or
HP lost to cold requires adequate shel-
ter and a heat source (flame, electric
heat, body warmth, etc.)."
What counts as 'adequate'? Judging by wording in High-Tech, tents, sleeping bags etc. count as shelters. But what about the heat source - is a fire the bare minimum for recovering cold FP? Or is one's own body heat from basic metabolism (assuming sufficient food etc.) enough if one loses FP to cold slower than once per 10 minutes (the standard cycle of FP recovery)?

Thanks in advance!

[Þorkell]

Originally Posted by vicky_molokh

Greetings, all!

I'm curious about the various nuances of cold hazards.

Fast wind forces HT checks to occur every 15 or 10 minutes instead of every 30. However, fast winds also reduce the effective temperature, which adds penalties to the HT roll. I don't get it. This looks suspiciously like double dipping. I thought that effective temperature from wind chill already includes the nastier cooling in such weathers. But it seems that as-is, -30°F real temperature at zero wind is better than -30°F effective temperature with fast wind (i.e. when the temperature is much higher, but counts as -30°F after adjustment for wind). What gives?

In my experience, though not at -30°F (and seriously, I had to use Google to figure how cold that was in units I can understand). not having any wind at all makes it feel as it's not as cold as the thermometer says.

[vicky_molokh]

Originally Posted by Þorkell

In my experience, though not at -30°F (and seriously, I had to use Google to figure how cold that was in units I can understand). not having any wind at all makes it feel as it's not as cold as the thermometer says.

Well, I tend to think in °C, but the temperature zones and modifiers are calculated based on °F.

Anyway, my point was the following bit seems weird to me:
Actual -30°F / -34°C at no wind is an effective temperature of -30°F / -34°C after (zero) wind chill adjustment; requires a HT-3 roll once per 30 minutes.
BUT
Actual 3°F / -16°C at 30m/s wind is an effective temperature of -30°F / -34°C too, which also requires HT-3 rolls . . . but once per 10 minutes.

[Varyon]

Originally Posted by vicky_molokh

Fast wind forces HT checks to occur every 15 or 10 minutes instead of every 30. However, fast winds also reduce the effective temperature, which adds penalties to the HT roll.

Yeah, this really stinks of double-dipping. Windchill could be represented by more frequent HT checks (as it's leeching heat from your body more rapidly) or a reduction in effective temperature. I don't think it should be both.

Originally Posted by vicky_molokh

Cold checks start at 35°F and below. Winter clothes provide +0 to those checks, no or light clothes provide -5 to them. What's the point of 'normal' clothing as far as staying warm goes? It doesn't seem to serve any niche game-mechanically.

More realistically, cold checks probably start higher than at just-above-freezing, and normal/light clothing would add to HT rolls there. I think GURPS has opted to just ignore this for simplicity's sake.

Originally Posted by vicky_molokh

Wet clothing gives an additional -5 to HT checks to resist cold, which is as bad as no clothing [...] is it really better to strip naked after climbing onto the shore from under the ice?

Evaporation of water is one of the most effective methods available for getting rid of heat, and water itself can absorb heat rather effectively. The body has a variety of ways to keep itself from losing heat too quickly even in rather cold temperatures, but those don't work so well when there's a layer of water on top of the body, leeching precious heat away. I'd argue that soaked-through clothing, regardless of its thickness, should be treated as normal wet clothing, for a total of -10. You need to get that winter/arctic clothing off immediately to get things to "only" -5, then you'll need to find a way to dry them out so you can put them back on to bring yourself back up to +0 or +5.


I'll have to think a bit about frostbite and get back to you on it. I will say that "exposed" isn't necessary, but is typically the case (and note that "wet clothing on it" is functionally "exposed"), and frostbite damage should typically start with the digits, then go to extremities followed by limbs.

[Flyndaran]

Clothing should alter temperature tolerances and/or ranges, not give bonuses to Ht rolls.
A warm jacket plus regular clothing kept me comfy down to 0 F for as long as I wanted.

[Varyon]

Originally Posted by Flyndaran

Clothing should alter temperature tolerances and/or ranges, not give bonuses to Ht rolls.
A warm jacket plus regular clothing kept me comfy down to 0 F for as long as I wanted.

Yeah, this is probably more appropriate. A character's temperature tolerance should probably be written assuming normal clothing. Light clothing would shift it up a bit; no clothing would shift it up more. Heavy/winter clothing would shift it down some, arctic clothing would shift it down quite a bit.

[vicky_molokh]

Originally Posted by Flyndaran

Clothing should alter temperature tolerances and/or ranges, not give bonuses to Ht rolls.
A warm jacket plus regular clothing kept me comfy down to 0 F for as long as I wanted.

That's an interesting mechanic. I wonder why it was not proposed / rejected throughout the four editions. It seems somewhat smoother than the current mechanic.
Though I think that in an ideal world, at whatever temperature HT checks for FP loss begin, they should begin at HT+6 and go down from there with temperature. Otherwise there's too huge a jump for HT10 normal-fitness characters unless they're wearing arctic clothing at 35°F / 0ish °C.

[Varyon]

Originally Posted by vicky_molokh

It seems somewhat smoother than the current mechanic.

Smoother, yes, but less consistent with other mechanics. GURPS is typically a system where equipment (or lack thereof), traits, and situations either give a bonus/penalty or make a percentage-based modifier to a situation. A Feature-style shift of "comfort zone" isn't anything like one of those, although it makes a great deal of sense.

Originally Posted by vicky_molokh

Though I think that in an ideal world, at whatever temperature HT checks for FP loss begin, they should begin at HT+6 and go down from there with temperature. Otherwise there's too huge a jump for HT10 normal-fitness characters unless they're wearing arctic clothing at 35°F / 0ish °C.

I agree (well, mostly; I'd probably be more inclined to go with something like "effective HT 18+ means no roll needed, anything lower needs one," or maybe a system that converts from a die roll to a consistent loss of FP based on HT). I think the reason why they didn't bother starting at, say, HT+6 is because making nuisance rolls can be annoying, even if it adds a bit more realism to the system.

[Edris]

Frostbite happens when cellular tissue freezes. Among other things, cells can burst open during this process, this is actual damage being done to the body. (Acute somatic damage, as the box frostbite says.) I'm assuming frostbite is an optional rule because it implies using accumulated wounds, another optional rule. As per when to apply the damage, it's whenever a location is exposed. I actually don't really understand the confusion here, unless you're wondering about normal clothing vs winter clothing for counting exposure. Per FP lost due to cold (Hypothermia) exposed hit locations lose 1 HP eventually crippling them (permanently, even). This is real, cellular damage; the damage is as injurious as being hit by a hammer.

The damage of frostbite crippling limbs accurately models real-world behavior in that when your body is subject to cold, blood vessels constrict to keep your core warm (and thus, you actually alive). Blood supplies oxygen (among other things) to your tissues, and removes waste from tissues, thus keeping them alive. When blood vessels constrict, your tissues get less oxygen supplied and less waste removal which results in cell death. Depending on the health of the victim, this can result in varying levels of injury; if someone is weak enough (typically older adults), sheets putting pressure on their toes can cause pressure sores (which are caused by lack of blood flow) as an example. As a result of all this, you suffer cell death (HP loss) upon loss of enough metabolic resources (FP loss). The amount of metabolic resources required to induce FP loss is linked to your overall health (HT check). Once your limbs unfreeze, normal metabolic processes return to normal and oxygen/waste removal is started again. If enough cellular damage has taken place, limbs/extremities/fingers may develop gangrene as a result of massive tissue death and may never actually recover (Permanent crippling).

Hypothermia is metabolic damage (As per the frostbite box) as you only lose HP indirectly via FP loss. This is your body running out of resources to maintain homeostasis, eventually you'll use enough that you'll run out and homeostasis will fail. Largely, this will start resulting in cell death (HP loss) as various bodily processes fail, eventually leading up to death.


Normal clothing doesn't give a bonus probably because T-Shirts and pants just don't really seal in heat very well over the long timescales that are relevant to hypothermia, especially if there's any airflow going on through your outfit via wind ("Must be insulated or heated to shield against prolonged exposure to ambient cold." (Basic - Campaigns P.430)) (For an outfit to count as winter clothes, it must protect the whole body against heat loss (High Tech P.63)).

If you want a niche for normal clothing; normal clothing, by a literal reading of the frostbite box, would confer protection from frostbite because it would mean a hit location is no longer exposed as it does not differentiate between levels of exposure between clothing. I, personally, have no idea how realistic this interpretation is so I can't comment; not a survivalist.

As for wind double-dipping, the following is my take on it.
As a human, you're largely water; water likes to evaporate in the atmosphere. Thus, we double-dip on convention with this and one of the primary ways we radiate heat is by evaporative cooling. By letting the water in our bodies evaporate (an endothermic reaction) we cool down. When there's more air flow moving over water, it evaporates faster. Although our outer skin is mostly dry and hydrophobic, there's still a certain amount of transepiderminal water loss. Thermal radiation in an atmosphere is primarily through physical contact with other things, typically atmospheric gases. When the gases aren't moving as a result of weather (Zero wind) you have gas that was warmed by your body heat staying near you longer. When the gases are moving by weather (Measurable wind speeds), that warm air is moving away from you faster and you're shedding more heat to the cooler air. Convention happens faster with a greater difference between two temperatures, and thus you're losing heat faster when there's more wind both by convention happening faster and evaporative cooling happening faster. This results in faster HT checks because you're cooling significantly faster, and HT penalties to these checks because you're literally more cold due to quicker convention and being cooled via evaporative cooling. Clothing gives a bonus to these HT rolls because it makes your body warmer by trapping in heat and offering vital protection against convention and evaporative cooling. Essentially, HT rolls are given bonuses and penalized by your own personal average temperature, which is why clothing gives a bonus.

As for adequate shelter and heat source.. I would say define it as anything that provides a full environment that provides a warm environment to your entire body simultaneously. I would not rule that a lone sleeping bag in the middle of the arctic is enough to regain FP loss due to cold, unless you could seal it around yourself entirely. As for the heat source, anything that keeps the environment at a moderate temperature that does not place stress on homeostasis so that your body can actually recover instead of having to actively spend metabolic resources to maintain homeostasis. I would say allowing for normal body metabolism to count as the heat source would require a very insulated tent or other shelter that leaks heat very slowly, and only once you've warmed up the inner environment enough to not place strain on homeostasis.

Just my thoughts as someone going into the nursing field and someone with an interest in science.

[vicky_molokh]

Originally Posted by Edris

Frostbite happens when cellular tissue freezes. Among other things, cells can burst open during this process, this is actual damage being done to the body. (Acute somatic damage, as the box frostbite says.) I'm assuming frostbite is an optional rule because it implies using accumulated wounds, another optional rule. As per when to apply the damage, it's whenever a location is exposed. I actually don't really understand the confusion here, unless you're wondering about normal clothing vs winter clothing for counting exposure. Per FP lost due to cold (Hypothermia) exposed hit locations lose 1 HP eventually crippling them (permanently, even). This is real, cellular damage; the damage is as injurious as being hit by a hammer.

The damage of frostbite crippling limbs accurately models real-world behavior in that when your body is subject to cold, blood vessels constrict to keep your core warm (and thus, you actually alive). Blood supplies oxygen (among other things) to your tissues, and removes waste from tissues, thus keeping them alive. When blood vessels constrict, your tissues get less oxygen supplied and less waste removal which results in cell death. Depending on the health of the victim, this can result in varying levels of injury; if someone is weak enough (typically older adults), sheets putting pressure on their toes can cause pressure sores (which are caused by lack of blood flow) as an example. As a result of all this, you suffer cell death (HP loss) upon loss of enough metabolic resources (FP loss). The amount of metabolic resources required to induce FP loss is linked to your overall health (HT check). Once your limbs unfreeze, normal metabolic processes return to normal and oxygen/waste removal is started again. If enough cellular damage has taken place, limbs/extremities/fingers may develop gangrene as a result of massive tissue death and may never actually recover (Permanent crippling).

Hypothermia is metabolic damage (As per the frostbite box) as you only lose HP indirectly via FP loss. This is your body running out of resources to maintain homeostasis, eventually you'll use enough that you'll run out and homeostasis will fail. Largely, this will start resulting in cell death (HP loss) as various bodily processes fail, eventually leading up to death.

I'm puzzled about nuances of frostbite because (a) I've seen/heard cases of frostbite affecting e.g. toes, and surely arctic explorers wouldn't have their feet exposed during travels, (b) there is a warning not to 'defreeze' extremities unless one is sure that warmth can be maintained, so that seems to indicate that damage works not from cold exposure alone.

Originally Posted by Edris

Normal clothing doesn't give a bonus probably because T-Shirts and pants just don't really seal in heat very well over the long timescales that are relevant to hypothermia, especially if there's any airflow going on through your outfit via wind ("Must be insulated or heated to shield against prolonged exposure to ambient cold." (Basic - Campaigns P.430)) (For an outfit to count as winter clothes, it must protect the whole body against heat loss (High Tech P.63)).

If you want a niche for normal clothing; normal clothing, by a literal reading of the frostbite box, would confer protection from frostbite because it would mean a hit location is no longer exposed as it does not differentiate between levels of exposure between clothing. I, personally, have no idea how realistic this interpretation is so I can't comment; not a survivalist.

Hmm. Just for a bit of calculation: it takes 2×(More Than HP/3) injury to permanently cripple an extremity. So at least 8 HP per hand for a typical person, and there doesn't seem to be a reason for all frostbite damage to concentrate on a single extremety. That seems to indicate that frostbite is unlikely to be a serious problem until a person risks unconsciousness and subsequent death anyway.

Originally Posted by Edris

As for wind double-dipping, the following is my take on it.
As a human, you're largely water; water likes to evaporate in the atmosphere. Thus, we double-dip on convention with this and one of the primary ways we radiate heat is by evaporative cooling. By letting the water in our bodies evaporate (an endothermic reaction) we cool down. When there's more air flow moving over water, it evaporates faster. Although our outer skin is mostly dry and hydrophobic, there's still a certain amount of transepiderminal water loss. Thermal radiation in an atmosphere is primarily through physical contact with other things, typically atmospheric gases. When the gases aren't moving as a result of weather (Zero wind) you have gas that was warmed by your body heat staying near you longer. When the gases are moving by weather (Measurable wind speeds), that warm air is moving away from you faster and you're shedding more heat to the cooler air. Convention happens faster with a greater difference between two temperatures, and thus you're losing heat faster when there's more wind both by convention happening faster and evaporative cooling happening faster. This results in faster HT checks because you're cooling significantly faster, and HT penalties to these checks because you're literally more cold due to quicker convention and being cooled via evaporative cooling. Clothing gives a bonus to these HT rolls because it makes your body warmer by trapping in heat and offering vital protection against convention and evaporative cooling. Essentially, HT rolls are given bonuses and penalized by your own personal average temperature, which is why clothing gives a bonus.

But AFAIK the existence of effective temperature is precisely the thing that was caused by needing a way to indicate 'more cooling' as adjusted for wind?

Originally Posted by Edris

As for adequate shelter and heat source.. I would say define it as anything that provides a full environment that provides a warm environment to your entire body simultaneously. I would not rule that a lone sleeping bag in the middle of the arctic is enough to regain FP loss due to cold, unless you could seal it around yourself entirely. As for the heat source, anything that keeps the environment at a moderate temperature that does not place stress on homeostasis so that your body can actually recover instead of having to actively spend metabolic resources to maintain homeostasis. I would say allowing for normal body metabolism to count as the heat source would require a very insulated tent or other shelter that leaks heat very slowly, and only once you've warmed up the inner environment enough to not place strain on homeostasis.

Hmm, thanks, that's actually an interesting idea. Now I have to wonder how to estimate when a given combination of one or more of body warmth, fire, and isolation (tent, sleeping bag and/or suit) is enough to create a non-freezing environment for the person involved.

Originally Posted by Edris

Just my thoughts as someone going into the nursing field and someone with an interest in science.

Thanks.

Also, weird coincidence: my survival-oriented questions are mostly related to preparing to play a survival-oriented character in an upcoming campaign; and the most likely name for the character was/is Edris (picked maybe a month or a half ago).