RE: [Leica] wind-chill

[Buzz Hausner <Buzz@marianmanor.org>]

Just a bit of history.  The "Wind Chill" factor was developed by the
geographer and arctic explorer, Paul Siple, while doing research initially
for his Ph.D. in geography from Clark University.  Siple was working under a
contract with the United States Navy and his mission was to determine the
combined effect of air temperature and wind on exposed skin, specifically,
to determine the curve of temperature and wind combinations at which exposed
human flesh was damaged.  Subsequently, Siple's research has been used to
try and establish the greatly more subjective effect of ambient temperature
and wind on human comfort, but this wanders far from the original intention
of the wind chill factor.

	Buzz Hausner, Geographer

- -----Original Message-----
From: Martin Howard [mailto:howard.390@osu.edu]
Sent: Saturday, December 23, 2000 7:33 PM
To: leica-users@mejac.palo-alto.ca.us
Subject: Re: [Leica] windchill
(sigh)

Windchill is a psychological effect.  Is the is perceived "coldness" of the
air when there is wind present.  In terms of "temperature" it only affects
living organisms comprised primarily of water.  Non-living matter is
affected by the wind only with regards to how quickly its temperature will
drop to that of the ambient level.  It will not go below this.  So, if the
ambient temperature is 5F, then the coldest your tripod/camera/whatever will
get is 5F, regardless of whether there is a gale-force wind blowing or not.
It'll *reach* 5F sooner in a gale-force wind, though (assuming it hasn't
blown off ;)

The psychology comes into it because to humans, 5F with a certain wind force
will *feel* like -39F without any wind at all.  It's all because our body is
working overtime (due to increased evaporation) to keep our internals cozy
and warm.

Which is where anyone with any sense chooses to be when the windchill
reached -39F.

Now, all of you with degrees in geophysical fluid dynamics, specifically
boundary layer climates, are welcome to start a new thread were you beat
this issue to death.  Please mark it "OT: Martin's dead wrong (was:
windchill)" so that I can automatically forward all the messages to my trash
can... ;)

M.

- -- 
Martin Howard                 | "We can't make mistakes like that on our
Visiting Scholar, CSEL, OSU   |  own. We need computers to help us."
email: howard.390@osu.edu     |     -- A pharmacologist on computerization
www: http://mvhoward.i.am/    +-------------------------------------------