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From: akcs.joehorn@hpcvbbs.UUCP (Joseph K. Horn)
Newsgroups: comp.sys.handhelds
Subject: Re: Wind Chill Index
Message-ID: <279d5175:1544.4comp.sys.handhelds;1@hpcvbbs.UUCP>
Date: 23 Jan 91 09:40:15 GMT
References: <15458@ogicse.ogi.edu> <27838cb8:1544.3comp.sys.handhelds;1@hpcvbbs
Lines: 32

M. Edward Borasky posted two equations for the Wind Chill Index
recently.  It reminded me of the BURR (as in "Brrrrrr!!!") routine
that was in the VOYAGER program written by Dr. Robert Wilson for
the HP-71 onboard the historic round-the-world Voyager aircraft
flight in 1986.  Here's that subprogram rewritten in 48 RPL:

-------------- CHILL in --------------
%%HP:T(3)F(.);
\<< 3.4759 MAX 50 MIN 4.63 * 9 / SWAP 32 - 5 * 9 / \-> v t
'33-(10.45+10*\v/v-v)*(33-t)/22.03405' 9 * 5 / 32 + 1 RND \>>
-------------- CHILL out -------------

This takes a Fahrenheit temperature in level 2, and a wind speed
in knots in level 1.  (Change it to mph if you want.)  The result
is not a Wind Chill Index, but the "apparent temperature" with
the wind chill factor already figured in.

So if you're skiing downhill on a 15 degree day with a 30 knot wind
sanding your face, this program says that it'll FEEL like it's
27.5 degrees below zero!  Until frostbite sets in, of course.

What I find odd is that if it's cold and windy enough, the result
can be far below absolute zero.  We must ponder this mystery...

Also, 91.4 degrees seems to be a turning point; above that, and
wind makes it seem HOTTER, not cooler!  Seems to me that the magic
number should be 98.6 ("... when it's difficult to tell where you
end and the night begins."); I'd LOVE a breeze on a 95 degree day!

--  Joseph K. Horn  --  (714) 858-0920  --  Peripheral Vision, Ltd.  --
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             |  "Many are cold, but few are frozen."  |
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