Chris Malcolm <cam.TakeThisOut@holyrood.ed.ac.uk> wrote:
>In rec.photo.digital.slr-systems Floyd L. Davidson <floyd.TakeThisOut@apaflo.com> wrote:
>We're both very obviously talking about temperatures pretty close to
>zero centigrade. You've specifically said that those are the
And you specifically indicated to start with that you
didn't then even realize that: Until I corrected you it
was "very serious cold", in your words.
Now, to read this article, you invented the idea!
A real hoot...
>> And I do realize that it is difficult for someone, like
>> yourself, who lives in a very temperate climate, to
>> understand references to things which only exist in
>> climates such as here in the Arctic, or the Antarctic.
>
>It's also completely irrelevant, because as you have already pointed
>out, the temperatures in question are around zero centigrade, which
>I'm sure both of us have plenty of experience with.
That is exactly the problem! You think that walking
around in Scotland on a cool day is the same as taking a
zodiac ride to an island in Antarctica on a warm day.
It is not the same.
>> Which is exactly why I pointed out that we are talking
>> about the weather in the *spring*, as opposed to weather
>> in the fall.
>
>Please cite what temperatures you're actually talking about in terms
I cited that right to start with, because *you* were going off the
deep end with a discussion of "very serious cold", which it is not.
However, you still haven't figured out that it *does*
make a difference whether it is 0C in the spring or 0C
in the fall. Your armchair experience is failing you.
>of numbers. I think we're talking about temperatures close to zero
>centigrade, and you're trying to confuse the issue in order to posture
>and sneer.
It is *not* posturing or sneering to correct the invalid
assumptions you _continue_ to post as fact.
>> I doubt that you can quite visualize that
>> to the degree that is just blatantly obvious to someone
>> who lives on the Arctic Ocean coast.
>
>I'm quite happy to accept your basic and completely irrelevant point
>that you've been a lot colder than I ever will be.
Please cease the armchair expert mode, and start
listening. It is relevant, and specifically is the
reason you statements continue to require correction.
>>>>>Under those conditions you have to wear enough
>>>
>>>> Under what conditions? You haven't got a clue, either
>>>> about the conditions or what one would wear there.
>
>If I haven't got a clue, why aren't you correcting me? You've spent a
lot of words correcting you...
>>>I know the temperature is around zero centigrade, and I know that
>
>> That isn't what anyone would normally expect to call
>> "serious".
>
>Scientists invented numerical temperature scales in order to stop
So why were *you* talking about "very serious cold".
Now that I've gotten it solidly through your head that
we are not talking about anything like that, you want to
claim it was your idea originally. But that is not what
you posted until I corrected you.
>people having this kind of silly argument about how whether a lump of
>melting ice is seriously cold or not.
Yeah, silly to an armchair explorer who lives in a
temperate climate; but not to people who are in
Antarctica.
>> You can also trust that someone who lives in Barrow gets
>> more experience in one winter with cold weather living
>> than you will living in Scotland in an entire life, if you
>> make it to 120 years old.
>
>So you keep saying, and I'm quite happy to accept that, especially
>since it has nothing to do with the topic of this thread.
You obviously haven't accepted it yet. It has to do
with who *is* an authority on the topic of discussion.
It is not insignificant either, except to an armchair
explorer.
>> The problem, which is what I was trying to point out
>> above, is that for different people the effects are
>> different. There is a *vast* difference between the way
>> someone acclimated to weather in Miami Florida handles a
>> windchill close to 0F and the way someone who has lived
>> a few years in Barrow Alaska does.
>
>I know that. The topic under discussion is the effect of temperature
>changes on cameras, which as far as I know do not adapt to different
>climates in the way that people do.
The topic is not just the camera, it is what sort of
clothing or other accessories are appropriate and or
necessary for such a visit.
>>>Many special fabrics have been devloped which
>>>facilitate the wicking or transpiration of moisture while being
>>>relatively wind proof.
>
>> Look, Eskimos have known exactly how to do that for a
>> few thousands of years. There isn't any need for
>> "special fabrics".
>
><sigh> I was including the clothing used by eskimos and other northern
>hunters in "special fabrics".
Nice attempt at back pedaling, but that is clearly not
what you said.
>The point, as I'm sure you realise, is
>that clothing which doesn't address these special problems won't keep
>you alive in those temperatures. And my specific point is that *any*
>kind of clothing which does address those special problems will
>necessarily have a moisture gradient as well as a temperature gradient
>after having been worn for a while.
You are describing something unrelated to temperature.
It's relative humidity that makes that type of situation
significant. It might be likely that where *you* live,
that it is important. But at higher latitudes it is
not, and the concept it implies can in fact get you into
trouble.
>> In cold weather, wicking is generally a *bad* idea. Air
>> circulation is the way to do it. Take a good look at a
>> decent parka design. Open at the bottom, lots of room,
>> and a hood that is an integral part of the trunk. The
>> best will not have a zippered front, but that is a
>> convenience that most people will want anyway; it just
>> needs be done as well as possible, with flaps both
>> behind it and in front, with buttons or velcro to secure
>> the front one.
>
>That's one way of solving the problem.
That is the right way. It is appropriate for the area the
OP will be traveling to.
>Another way is the use of what
>are sometimes called "breathable" fabrics.
Which is a mistake.
....
>> Air moves up through the parka. If it is too tight
>> fitting for air movement, it will not keep you warm.
>
>If used in the way you specified, but there's more than one way of
>solving these cold weather clothing problems.
From an armchair...
>>>Pretty much any serious outdoor cold weather
>>>coat will incorporate one or another kind of such technology whether
>>>you are aware of it or not.
>
>> Have you actually ever been outside in cold weather?
>> Say 24 hours at -60F?
>
>I'm quite happy to acknowledge your superior expertise in very cold
>conditions.
Then stop posting garbage, claiming you know what you
haven't a clue about.
>I've worn out two mountain coats in the last few decades without
>getting anything close to hypothermia, even in temperatures cold
>enough that if I didn't keep opening my mouth my breath froze my beard
>right over my mouth in less than a minute.
My oh my, aren't you just a wonderful example of an
intrepid Arctic Explorer yourself.
>I think we may be talking at cross purposes here. When I say "moisture
>gradient" I'm talking about the water vapour content of the air, I'm
>not talking about actual wet liquid water. It's the water vapour
>content that causes condensation on cold surfaces, which is what
(Actually, the words you are looking for would be "vapor
pressure", but I'll stay away from the level of
technicality to avoid further confusion. But if you
want to understand this topic, that is the term to do a
search on.)
>happens when you put a freezing camera into a warm dry atmosphere, but
>one which has more water vapour in the air than can be held in air at
>the temperature of the camera.
If there is air from outside the coat slowly circulating
up from the bottom to the top, there is no moisture
gradient. The air, as it circulates, carries the )very
small amount of) moisture your body produces out with it.
The only way to have a moisture gradient is with a
poorly design coat. It should be replaced. And indeed,
it is only with a properly designed coat that there is
enough room inside the coat to keep a typical DSLR under
wraps!
>The presence of a water vapour gradient inside cold weather clothing
>doesn't give anyone hypothermia,
Armchair exploration proves that to be true... as long
as you stay in an armchair. The real world is
different...
The presence of a water vapor gradient in cold weather
will kill you. Dead. Today it is slightly less of a
problem simply because we have developed a few water
proof synthetic insulators that work almost as well as
down, and they are commonly used. With a down parka
that gradient slowly destroys the ability of down to
insulate.
>and it's an inescapable physical and
>physiological consequence of wearing thermally insulating clothing
>over a warm human body in the cold.
Nice armchair son. Where did you order it from?
>Will you please stop posturing about the heroically cold conditions
It is a _fact_ that I do live in a cold climate,
and necessarily get more experience each month during
any one winter than you will get in your entire life
sitting in that armchair.
>you live in, and try to remember the topic of this discussion, which
>is the characeristic summer temperatures in the South Shetlands? I
>believe that those temperatures are around zero centigrade, which
>wimpishly mild temperatures I do have plenty of experience with.
Why did you call it "very serious cold"? Did it appear
to be that, from your armchair, before I started
correcting you?
>Calm down Floyd! I quite happily accept that you're a hero with a
>lifelong experience of temperatures vastly colder than I'll ever
>experience. The topic under discussion here is the temperatures in the
>South Shetlands in the summer -- which are around zero centigrade. I'm
It took how many exchanges for you to agree that it is
not a "very serious cold" situation? Regardless, lets
do keep in mind that weather at those latitudes, during
the warmest time of the year, is not anything like
weather at your latitude during the coldest time of the
year, even if the temperatures actually do come close on
occasion.
>> I expect that judging an Arctic environment by what you
>> can experience in Scotland is a potentially fatal error.
>
>Please stop posturing and start talking in terms of numbers. I
You've done little other than posturing, from an armchair.
>understand that the temperature in the South Shetlands in the summer
>is around zero centigrade. I have plenty of experience of that kind of
>temperature.
Really? Ever been on board a ship scooting past an
ice floe? Or pulled up on a snowed in beach in a zodiac
after dodging ice floes to find a landing area?
I don't think your armchair power controls are ready for
the South Shetlands, never mind the Antarctic Peninsula.
>> You don't realize that trapping water vapor inside your
>> coat in the manner you are describing is *deadly* around
>> here.
>
>I think you must have been looking out of the window in your school
>physics classes.
Here we go again, with another absurdly *incorrect*
theory of how things work from an armchair explorer.
>If it was trapped there wouldn't be a gradient. What
>causes the gradient is the *movement* of the water vapour.
If it *isn't* trapped, there can be no gradient, and it
is insufficient movement that causes a gradient. (I.e.,
you have it exactly backwards, again.)
If there is sufficient air movement, the vapor is
equally dispersed. If movement is impeded, a gradient
can form. If it is impeded enough, a significant
gradient forms, and that commonly results in ice
*forming* *in* *the* *insulation*, which quickly reduces
the quality of the insulation to zero.
For a person depending on a coat to retain body heat
over an extended period of time, a temperature gradient
can be fatal. (The length of time decreases as the
temperature drops, though hypothermia is a very common
problem at temperatures well above freezing.) The loss
of insulating quality due to trapped air that allows the
build up of a moisture gradient can be fatal. That is
true if there is not an adequate "vapor barrier", and in
fact some clothing ("bunny boots" being the best known
example) is designed on the principle of an very good
vapor barrier. But coats do not work the way bunny
boots do, because a similar seal is impossible, and a
flawed seal is fatal.
>> In Edinburgh Scotland, yes. A wonderful place with a
>> very mild temperate climate... on your coldest month
>> the average low temperature is 0C.
>
>Which as it happens is the temperature of the South Shetlands in summer.
And your ice floes are the same?
>> (The average low in
>> that month here is -30C.)
>
>Which as it happens is *not* the temperature in the South Shetlands in
>the summer.
But our ice *is* the same.
>Experience in zero centigrade conditions, which you seem happy to
>admit I do have, is relevant to travel in the South Shetlands in
>summer because the temperature there and then is also around zero
>centigrade, is it not?
It would be if you didn't try to extrapolate what little
you know to things that are seriously important and
outside the scope of your knowledge. You started off by
claiming this was all about "very serious cold", and it
has taken how many exchanges to get you to realize that
it is *not*. So now you claim to have invented the idea
that it actually is about some fairly mild weather
conditions...
But there are still a lot of variations from what you do
know about. You obviously have very little real
understanding of how warm clothing functions, as one
example. And much of what you cite is traditional
knowledge that historically was useful in relatively
damp areas that barely get cold. Scotland is very
similar to Southeast Alaska. Both areas are a northern
maritime climate, warmed by an ocean current from the
south. You probably don't get as much rain on the
eastern side of Scotland as they do along the western
coast of Southeast Alaska, but the problems of staying
warm in a moist climate are at least similar.
The high latitude maritime climates are different, and
traditional clothing is different.
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd.TakeThisOut@apaflo.com
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