Avoid Delta and Atlanta

Mxsmanic wrote:
It doesn't. But it speeds evaporation of sweat by increasing air
movement. The sweat thus evaporated increases the amount of water
vapor in the air, thereby increasing relative humidity.

Evaporation of sweat is excatly what keeps your body cool. As it
evaporates, it absorbs heat from your skin. And this is why/how sweating
allows your body to keep a temperature that is below ambiant
temperature.

And unless you are in an enclosed, air tight car, the amount of water
you release into the air will just flow out of the room due to the fan
pushing it out.

nobody writes:

Evaporation of sweat is excatly what keeps your body cool.

It's also exactly what increases humidity in the room. The more sweat
that evaporates from your body, the higher the humidity gets, and the
harder it is to keep cool through evaporation of sweat (because it
evaporates more and more slowly as room humidity increases). This
creates a vicious circle of ever-increasing sweat and discomfort,
until the room humidity reaches 100%, at which point no amount of
sweating will provide any cooling at all, no matter how powerful the
fan. Heat exhaustion or heatstroke will often be a risk before this
point is reached, however.

And unless you are in an enclosed, air tight car, the amount of water
you release into the air will just flow out of the room due to the fan
pushing it out.

Typically fans are positioned such that they just move air around in a
closed room. There may be little or no connection to the outside
world, and certainly not enough to effectively exhaust humid air.

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"Mxsmanic" wrote in message
...
nobody writes:

Evaporation of sweat is excatly what keeps your body cool.

It's also exactly what increases humidity in the room. The more sweat
that evaporates from your body, the higher the humidity gets, and the
harder it is to keep cool through evaporation of sweat (because it
evaporates more and more slowly as room humidity increases).


So you sit and sweat in an room with no ventilation !

It must be NASTY in there by now


This
creates a vicious circle of ever-increasing sweat and discomfort,
until the room humidity reaches 100%, at which point no amount of
sweating will provide any cooling at all, no matter how powerful the
fan. Heat exhaustion or heatstroke will often be a risk before this
point is reached, however.

And unless you are in an enclosed, air tight car, the amount of water
you release into the air will just flow out of the room due to the fan
pushing it out.

Typically fans are positioned such that they just move air around in a
closed room. There may be little or no connection to the outside
world, and certainly not enough to effectively exhaust humid air.


Psst windows can be opened, take a class.

Keith

On Mon, 24 Jul 2006 20:08:25 +0200, Mxsmanic
wrote:

nobody writes:

Evaporation of sweat is excatly what keeps your body cool.

It's also exactly what increases humidity in the room. The more sweat
that evaporates from your body, the higher the humidity gets, and the
harder it is to keep cool through evaporation of sweat (because it
evaporates more and more slowly as room humidity increases). This
creates a vicious circle of ever-increasing sweat and discomfort,
until the room humidity reaches 100%, at which point no amount of
sweating will provide any cooling at all, no matter how powerful the
fan. Heat exhaustion or heatstroke will often be a risk before this
point is reached, however.

I would say most would open a window or leave the room long before
that happened.

And unless you are in an enclosed, air tight car, the amount of water
you release into the air will just flow out of the room due to the fan
pushing it out.

Typically fans are positioned such that they just move air around in a
closed room. There may be little or no connection to the outside
world, and certainly not enough to effectively exhaust humid air.

Typically? Typically one opens the window if you are using a fan.

Perhaps this was your failing.
--
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DFM - http://www.deepfriedmars.com
---
--

"Mxsmanic" wrote...

nobody writes:

Evaporation of sweat is excatly what keeps your body cool.

It's also exactly what increases humidity in the room. The more sweat
that evaporates from your body, the higher the humidity gets, and the
harder it is to keep cool through evaporation of sweat (because it
evaporates more and more slowly as room humidity increases). This
creates a vicious circle of ever-increasing sweat and discomfort,
until the room humidity reaches 100%, at which point no amount of
sweating will provide any cooling at all, no matter how powerful the
fan. Heat exhaustion or heatstroke will often be a risk before this
point is reached, however.

Other than in a carefully designed laboaratory environment, constructing a
room that "airtight" would be virtually impossible. In "real"
circumstances, moisture movement into surrounding air occurs at about the
same rate as heat transfer. Obviousluy, a vast advantage of mechanical AC
is that the systems removes vast amounts of moisture as it chills the air,
dumping the condensate "overboard" at a high rate. Actually, the optimal
accomplishment of AC is dehumidification.

Survival in high temps involves a combination of efforts, staying out of
direct sunlight in which body temp rises due to radiant absorption, drinking
plenty of fluids to enourage sweating, and taking advantage of any breeze,
mechanical (fan) or natural to increase surface evaporation which acts to
cool the skin.

You're humidifying the air at a far greater rate through breathing (exhaling
moisture) than by skin evapaoration when the humidity is already high, so
under most heat conditions given eqial indoor and outdoor temperatures (or
higher indoor temps, under a black roof for instance), you're better off
getting the Hell outside (but in the shade).

Loose, light colored clothing which covers as much exposed skin as possible
also helps, and can amplify the cooling of evaporation.

Get outside and under a shad tree but with maximum exposure to any breeze.



And unless you are in an enclosed, air tight car, the amount of water
you release into the air will just flow out of the room due to the fan
pushing it out.

Typically fans are positioned such that they just move air around in a
closed room. There may be little or no connection to the outside
world, and certainly not enough to effectively exhaust humid air.

In a non-AC auto with the venting system opening and operating and a speed
of 30mph or so, total air exchange occurs in a meter of one or two minutes,
however, but stop the car and air exchange drops to minimal, while sunlight
heats the car rapidly and small children and the elderly can suffer rapid
loss of body fluids and go into shock (along with increased body temps).


There's more than enough moisture movement and air movement created by
simply opening a window. In multi story buildings, opening a ground floor
door and a roof door can vastly improve conditions, creating a chimney of
rapidly circulating air as hot air rises....

Those of us who grew up in areas with frequent summer temps of over 100F and
humdity well above 50% before the "spread" of AC remain pretty conscious of
fighting the heat, even now with AC prevalent.

Comparing temps....Move the thermometer 20 degrees (F) above normal body
temperature and most folks wouldn't last an hour. Move it 40 degrees below
and a light jacket maintains comfort. Where I live, were I asked to give up
heating or AC, the choice would be easy. Most nights, the day's sunlight
means that even a cold night (20F) will not drop the interior temperature in
my home below 55F, just at the cusp of good sleeping.

The problem in Paris is a population much of which is little acclimated to
high temps, unequipped with clothing or ventilation to function in them. and
if elderly particularly subject to heat.

TMO

TMO

Keith W writes:

So you sit and sweat in an room with no ventilation !

Without air conditioning, you sit and sweat in a room with or without
ventilation.

Psst windows can be opened, take a class.

Opening windows and getting air to move through them are two different
things.

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Dave Frightens Me writes:

I would say most would open a window or leave the room long before
that happened.

Opening a window may not be sufficient, and leaving the room may not
be an option.

Typically? Typically one opens the window if you are using a fan.

Just opening a window doesn't necessarily accomplish anything. Proper
ventilation requires more careful planning than that. And if it's hot
and humid, opening a window really accomplishes nothing at all.

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TOliver writes:

Other than in a carefully designed laboaratory environment, constructing a
room that "airtight" would be virtually impossible.

It doesn't have to be airtight; in fact, it doesn't even have to be
windowless. All it needs is poor ventilation, which is easy to come
by, unfortunately.

In "real"
circumstances, moisture movement into surrounding air occurs at about the
same rate as heat transfer.

That is to say, barely at all, in many cases.

Obviousluy, a vast advantage of mechanical AC
is that the systems removes vast amounts of moisture as it chills the air,
dumping the condensate "overboard" at a high rate. Actually, the optimal
accomplishment of AC is dehumidification.

Yes.

Survival in high temps involves a combination of efforts, staying out of
direct sunlight in which body temp rises due to radiant absorption, drinking
plenty of fluids to enourage sweating, and taking advantage of any breeze,
mechanical (fan) or natural to increase surface evaporation which acts to
cool the skin.

Sometimes that's not enough. In humid climates, no fan can blow hard
or fast enough to provide adequate evaporative cooling.

In general, if you notice any sweat at all on your skin, it is not
being evaporated fast enough to keep you cool. It builds up because
your body is trying to produce more sweat in order to improve
evaporative cooling, but the fact that it collects rather than
evaporates makes it clear that the needed cooling is not occurring.
Sensible sweating is thus an indication that environmental conditions
of heat and humidity are high enough to present a health hazard.

You're humidifying the air at a far greater rate through breathing (exhaling
moisture) than by skin evapaoration when the humidity is already high ...

No. In high humidity, you can lose litres per hour in evaporating
sweat, many times more than you lose through respiration.

... so
under most heat conditions given eqial indoor and outdoor temperatures (or
higher indoor temps, under a black roof for instance), you're better off
getting the Hell outside (but in the shade).

You're better off finding lower humidity, lower temperature, and
better air movement, without direct sunlight. Unfortunately,
sometimes these are not available, which is why air conditioning
exists.

Get outside and under a shad tree but with maximum exposure to any breeze.

What do you tell your manager in the office?

In a non-AC auto with the venting system opening and operating and a speed
of 30mph or so, total air exchange occurs in a meter of one or two minutes,
however, but stop the car and air exchange drops to minimal, while sunlight
heats the car rapidly and small children and the elderly can suffer rapid
loss of body fluids and go into shock (along with increased body temps).

Apartments are not automobiles. Changing the air in an apartment at
that rate practically requires a tornado (but Europe is starting to
get those, too).

In multi story buildings, opening a ground floor
door and a roof door can vastly improve conditions, creating a chimney of
rapidly circulating air as hot air rises....

Only if there's a connection between the two.

Modern, large buildings only became practical with the invention of
air conditioning.

Comparing temps....Move the thermometer 20 degrees (F) above normal body
temperature and most folks wouldn't last an hour.

That would be 118° F. An hour is probably an exaggeration, but many
would succumb within a few hours.

Move it 40 degrees below and a light jacket maintains comfort.

Yes. I have some light thermalwear that will keep me warm even at
temperatures of 15-20° F.

Where I live, were I asked to give up heating or AC, the choice would
be easy.

Same here. There are many ways to trap and retain heat; there are no
ways to remove heat without active refrigeration of some kind. I can
survive longer with no heat than with no cooling.

Most nights, the day's sunlight
means that even a cold night (20F) will not drop the interior temperature in
my home below 55F, just at the cusp of good sleeping.

The central heating in my building is so powerful that I often must
open windows or even turn on the A/C in winter to keep the apartment
cool. The heating really only matches the cold at temperatures below
freezing, and those are quite rare today.

The problem in Paris is a population much of which is little acclimated to
high temps, unequipped with clothing or ventilation to function in them. and
if elderly particularly subject to heat.

And a population that is massively ignorant of how to deal with heat.

But ultimately it boils down to air conditioning.

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On Mon, 24 Jul 2006 21:57:34 +0200, Mxsmanic
wrote:

Dave Frightens Me writes:

I would say most would open a window or leave the room long before
that happened.

Opening a window may not be sufficient, and leaving the room may not
be an option.

There is no situation where leaving the room may not be an option when
faced with death.

Typically? Typically one opens the window if you are using a fan.

Just opening a window doesn't necessarily accomplish anything. Proper
ventilation requires more careful planning than that. And if it's hot
and humid, opening a window really accomplishes nothing at all.

Try not opening it and see if it makes no difference.
--
---
DFM - http://www.deepfriedmars.com
---
--

"Mxsmanic" wrote in message
...
Keith W writes:

So you sit and sweat in an room with no ventilation !

Without air conditioning, you sit and sweat in a room with or without
ventilation.


No I open the windows and turn on a fan

Psst windows can be opened, take a class.

Opening windows and getting air to move through them are two different
things.


See FAN - Device for moving air - often powered by a small motor


Keith