On Thu, 08 Feb 2007 18:05:26 GMT, "Calif Bill"
wrote:


"Eisboch" wrote in message
...

"JoeSpareBedroom" wrote in message
...


What about when it hits the windshield, under those same conditions?


Wind will cause an object to lose heat faster ... but will not cool it
below the ambient temperature.

The evaporation of a liquid is a state change whereby energy is used and
heat is given off.

Wind chill is a measurement of rapid cooling of living tissue.

Eisboch

Wind Chill. I do not think it refers to living tissue. I think the
definition is how much heat transfer would occur in still air vs. Moving
air. some low speed of air. -15 degrees with a wind chill of -30, says the
same heat loss would occur if the temp was -30 and no wind movement.
Nothing to do with evaporation but with the tendency of the air to heat up
near the warmer object, slowing down heat transfer.

It's supposedly based on skin feel. Whose skin is up for debate.
There's a formula for it, but anybody who has spent time in the cold
knows that if the wind can make your nose freeze solid but if you
turn from the wind your nose is okay, the same procedure can apply
to your car's engine block when deciding whether it is best to park
facing the wind, or away from it.
Basically the term has been appropriated by weathermen to keep people
properly scared. Saw a map of temperatures the local joker put up
last night which gave me a momentary shock, until I realized it was
all wind chill temps. Yeah, like anybody knows how the winds are
blowing at these locations. It was inaccurate before it was posted.
As you said, it's all about heat transfer.
Just don't call it wind chill unless you're talking about human skin.
That's taken. Call it air chilled, then nobody can challenge you.

--Vic