On Friday, January 3, 2014 7:55:21 PM UTC-5, Gordon Shumway wrote:
On Fri, 3 Jan 2014 16:02:50 -0800 (PST), "

wrote:



On Friday, January 3, 2014 6:21:03 PM UTC-5, Gordon Shumway wrote:

On Fri, 03 Jan 2014 16:11:35 -0500, Stormin Mormon



wrote:







Tonight in NYS supposed to be 0F, and wind



chill -10 or so. Which number is the one



which concerns water pipes freezing?







I know the pipes won't get below the actual



temp, but are they more likely to freeze,



with wind?







Wind chill is the effect the combination of cold air and wind has on



exposed flesh relative to only cold air. "Wind chill" has absolutely



no effect on inanimate objects. The wind on an inanimate object will



cool an inanimate object to the ambient temperature quicker than no



wind.





Which of course means that wind chill does have an effect on inanimate

objects, in some cases.



No, no, no.



If you take an inanimate object like a brick

that's at 70F and put it outside where it's exposed when the wind chill

is 0F it's going to cool off faster than if you put it outside when

the wind chill is 15F, even if the actual temperature in both cases is 20F.

Once it's reached 20F, then it will have no further effect of any significance.



Yes, but the ambient temp in your example, is 20F. Wind chill does

not have time in its' calculation.



Of course it doesn't have time in it's calculation, which is irrelevant.
A bucket of 75F water placed outside when it's 20F with a wind chill of 0F
will freeze faster than it will when the wind chill is 17F. Therefore
windchill does matter with inanimate objects, in some cases.




In the case of freezing pipes, I would say in many cases wind chill does matter,



You would be wrong. If it is going to freeze it may do it sooner but

the pipe will not get colder than the ambient. Period.



That's like saying the pipes will freeze if they will freeze.
Sure, if you want to define ambient to be the temperature at the
pipes. But who measures that? The point is if one hears that
it's going to be 20F tonight, is there valid reason to be more
concerned about pipes in an outside wall, a drafty crawlspace,
etc freezing if the reported windchill is 0F versus 17F? The
answer to that is yes.





because any place that is drafty, or even an exterior wall, is going to

be effected by the wind. The pipe in the wall could be colder on a night

with a lower wind chill, even though the actual outside temp is the same.





It is impossible to get an inanimate object colder than ambient



temperature by using wind that is also ambient temperature.



Which shows that by ambient, you're using the outside air temp,
which is what most people would be looking at when trying to
decide it their pipes are going to freeze, because they have
no way of knowing what the ambient temp at the actual pipe inside
the wall is. Now, you're trying to change ambient into the
temp at the pipes hidden in the walls, which no one would even
know. It's simple. Whatever the reported outside temp is,
the lower the windchill, the greater the possibility that pipes
in an exterior wall, drafty crawlspace, etc will freeze.

Here's another question. If inanimate objects are not affected
by windchill, then on a night when the outside temp is 20F,
the same house is going to use the same amount of energy to
keep it at 70F when the windchill is 0F as it does if the windchill
is 17F?