My car starts reliably to -20F . The temperature outside it -18F but the
wind chill factor is -40F. Will my car start?
To all the science-minded people out there , the answer is "NO".
I am NOT going out to start it!
The phenomenon you're referring to is NOT "wind chill". The phenomenon
you're referring to is simply air movement stripping away or minimizing any
boundary layer, thus keeping the temperature gradient steeper than it would
be if a boundary layer were allowed to establish and thicken. That's why an
engine in the wind will cool faster than one in still air.
But either way, no engine will cool to BELOW AMBIENT, which is what the
term "wind chill" implies. The sensation of a below-ambient temperature can
only be felt by animate objects that generate their own heat. You, for
No, it's *exactly* wind-chill. It's exactly the same process that
makes you feel colder when the wind is blowing. Your body is required
to make more heat to keep its temperature constant. The "off" engine
doesn't generate heat, so gets colder, faster, in the wind.
The term "wind chill" is used to refer to the sensation of air /feeling/
colder than it actually is; it cannot apply to an inanimate object.
Your sentence does not appear to follow from my sentence that you quoted
My corpse will be an inanimate object that will not generate its own heat
and will thus be unable to feel "wind chill". Until I zombi-fy, of course.
True but irrelevant.
You originally said the ambient temperature was -18 with a wind chill of
-40, and implied that the wind chill would have some effect on the engine's
ability to start. Wind chill will have NO effect on the engine at all. The
engine knows it's -18 and no lower.
(krw appears to have been right that hastened cooling in wind is in fact
also called "wind chill".)
Now, hold on. I hate to put a wet blanket on this
conversation, but Philo and Tegger and myself have
said that wind chill doesn't prevent an engine from
starting due to temps colder than the ambient. We
did say that such engine cools faster than still
air. You can't just go around telling people that
we agree with each other. It's un-Democratic. What
would Jesse and Al say? And Papa Obama? What would
happen if EVERYONE agreed? Don't be telling me it's
just a couple people. What would happen if EVERYONE
That depends on how long it's left in the wind. It takes a looong
time for an engine to lose residual heat.
It'll take much longer to reach that -18 if parked out of the wind.
Parking a car in shelter can make a big difference.
The speed of cooling has different effects on
inanimate objects and biological organisms. For
inanimate objects, the effect of wind chill is
to reduce any warmer objects to the ambient
temperature more quickly.
Well, if I park a car facing cold Northerly wind vs. facing the other
way, one facing North is harder to start in the morning. In Chinese
wind chill spells like this, "體感溫度" direct translation, "temperature
feels like" which is usually lower than actual temperature. I am not
Cold wind is colder than ambient, right? Energy only flows in one
direction in thermo-dynamics when no extra energy is added. It is
possible for a high wind to take away a bit more energy than it
provides. However, it is still providing energy, so, the temperature
difference will be minute unless the wind is measurably colder.
Works in reverse, too. A real high wind, even if cold, will heat
an object. That's one hell of a wind, though. It is rather unlikely
to cause that much friction. Though, super sonic craft...
This is in no way a succinct description and is rather piss poor in my
opinion. Oh, well. Other things on my mind.
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