If anyone is curious if a Gladiator starts in -40...

[Gladiator4Runner]

I'm not going to debate this - physics is physics, and thermodynamics is thermodynamics, and I was trying to offer a simple explanation. In my post I was describing one way that objects lose heat (that's pertinent to the discussion). It's certainly true that the object (in the case of a warm-blooded animal) can be creating heat at the same time, and especially if insulated (thus slowing the heat loss), the rate of heat created can meet or even exceed the rate of heat loss. No object, living or not, will become colder than ambient, but every object, living or not, will lose heat faster in a wind that's constantly bring cold air next to it, maintaining a large temperature difference. Windchill is not an important concept with inanimate objects - they don't "feel" how quickly they change temperature - but it is inaccurate to suggest that their rate of heat loss is unaffected by wind.

You're exactly right. Just try grilling on a cool day vs. a cool day with wind. It'll mess with your grill temps bigtime!

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[jimbom]

I'm not going to debate this ... - .

Except that you just did ...

I'm not going to debate it either, but I will point out the opposite effect, where wind absolutely does affect the temperature of non-humans. Jeeps don't experience this effect, but supersonic aircraft do.

 

[jimbom]

If what you believe is true Lake Michigan would be frozen solid 10 months out of the year and Lake Superior would no doubt be a frozen glacier.

As already mentioned, evaporative cooling is intensified by wind, and those lakes can be colder than ambient because of that. In Arizona our swimming pools are usually colder than the average ambient temp due to low humidity and wind.

 

[Blade1668]

Ahh a nice balmy weather here... As I'm reading this 27 f as said on first page I started thinking about a cup of coffee
Good to hearing it start... Not sounding good but better than click click click. Back in early to mid 70s using a few metal pans with some charcoal burning slid under oilpan of car to warm it up. Trick was from a WW2 vet. His old Mercury. ( Put in pan light place second one on top to damper it) something you can do to modern vehicles I'd say.

 

[firemedic2714]

I haven't encountered any super cold weather here in St. Louis with my JT yet, but my '15 JKU always sounded unhappy when I started it in actual or close to subzero temps.

 

[Knightindullarmor]

So you are saying that ISU, all of the other meteorology schools, the meteorology sites, WIKIPEDIA and our earth sciences teacher are all full of BS?

Look it up - you'll get dozens of hits all saying the same thing - human perception, does not apply to inanimate objects.
Don't take my word for it.
Go for it - argue all you want with scientists who developed the wind chill idea and those who wrote those web sites I quoted.

I stand with science...... (and my son who went to meteorology school until he decided to change majors)
(I was a straight A science student if that matters)

A bottle of whisky cannot be any colder than the air around it. (unless you have a wet cloth around it - then the act of the wind evaporating the water from the cloth causes a cooling effect)

Not entirely true. Ambient humidity makes air "thicker" or "thinner". The amount of water vapor in the air (aka "humidity") can have a drastic effect on the ability of said air to heat or cool anything (both animate or inanimate). 50 degree air can be comfortable for hours in shorts and a t-shirt in low humidity. Swimming in 50 degree water for 15 minutes can produce hypothermia due to the denser substance wicking away more heat. But what the F do I know? I only had to endure naval/waterborne assault training off the VA coast in winter.

Your "science" dictates that ice cannot cool a soda or beer to below 32 degrees Fahrenheit. But experiments prove that ice + water combined can cool that same can of soda or beer to 29 degrees Fahrenheit. Humidity (air or surrounding material density) DOES have an affect.

 

[Knightindullarmor]

'Tis why engine temperature of 210 to 230 is "normal" even with water as coolant, even though water evaporates at 212.

 

[DailyMoparGuy]

Man I miss the snow in West Virginia. I sure love a true cold start too.

 

[ShadowsPapa]

Not entirely true. Ambient humidity makes air "thicker" or "thinner". The amount of water vapor in the air (aka "humidity") can have a drastic effect on the ability of said air to heat or cool anything (both animate or inanimate). 50 degree air can be comfortable for hours in shorts and a t-shirt in low humidity. Swimming in 50 degree water for 15 minutes can produce hypothermia due to the denser substance wicking away more heat. But what the F do I know? I only had to endure naval/waterborne assault training off the VA coast in winter.

Your "science" dictates that ice cannot cool a soda or beer to below 32 degrees Fahrenheit. But experiments prove that ice + water combined can cool that same can of soda or beer to 29 degrees Fahrenheit. Humidity (air or surrounding material density) DOES have an affect.

You can't cool something to LESS than what the media you are using to cool that item is. If the air temperature is 30, you can't use that 30 degree air to cool something down to 25.
Yes humidity has an impact, but the air won't take any more heat away from that item you are cooling once an equilibrium is reached.

In short, 30 degree air can't make any inanimate object 25 degrees.

 

[ShadowsPapa]

'Tis why engine temperature of 210 to 230 is "normal" even with water as coolant, even though water evaporates at 212.

Dunno what the hell that means LOL - nothing to do with the other.
The coolant is PRESSURIZED is why it's not boiling out. Further, the "antifreeze" raises the boiling point to well over 212. Not even related at all.
The water will absorb heat from the engine until the engine and water are equal temperatures (as long as it can't boil) but it can't cool the engine any further once they are equal temperatures. Heat energy no longer moves from one to the other.
The coolant then sheds its heat energy in the radiator.

Water doesn't "evaporate" at 212. Try science again.
I aced my science classes (as well as 4.0 in college)

 

[AKDrifter]

'Tis why engine temperature of 210 to 230 is "normal" even with water as coolant, even though water evaporates at 212.

That part has to do with the pressure being applied. I work in HVAC. Water at 15psi will not boil (I think is what you meant by evaporate) until it hits 257 degrees Fahrenheit. If for some reason you needed higher temps you'd just add some more pressure but I've never seen a boiler that would go anywhere near that high of temperature. You get about 3 degrees higher boiling point for every 1 psi. That's why they tell you to not open the radiator cap on your old cars when it's hot. It's set to hold a certain pressure on the system that happens naturally as the water expands. That's why it doesn't boil over.

 

[ShadowsPapa]

That part has to do with the pressure being applied. I work in HVAC. Water at 15psi will not boil (I think is what you meant by evaporate) until it hits 257 degrees Fahrenheit. If for some reason you needed higher temps you'd just add some more pressure but I've never seen a boiler that would go anywhere near that high of temperature. You get about 3 degrees higher boiling point for every 1 psi. That's why they tell you to not open the radiator cap on your old cars when it's hot. It's set to hold a certain pressure on the system that happens naturally as the water expands. That's why it doesn't boil over.

Ever seen a steam boiler go?
I used to collect and restore antique tractors, still have most of my antique engines. Because once there's a teeny little gap for the pressure to release through, the water boils instantly (well, pretty much) and it explodes. You take a cap off a HOT radiator and you not only have the escaping steam to deal with but now potentially allow that water to boil violently.

The pressure cap - and the fact it's mixed with antifreeze which is also anti-boil - that in itself raises the boiling point to 223 (for 50/50 ethylene glycol mix) Then add the pressure cap to that and it's well over 260.

 

[ShadowsPapa]

That part has to do with the pressure being applied. I work in HVAC. Water at 15psi will not boil (I think is what you meant by evaporate) until it hits 257 degrees Fahrenheit. If for some reason you needed higher temps you'd just add some more pressure but I've never seen a boiler that would go anywhere near that high of temperature. You get about 3 degrees higher boiling point for every 1 psi. That's why they tell you to not open the radiator cap on your old cars when it's hot. It's set to hold a certain pressure on the system that happens naturally as the water expands. That's why it doesn't boil over.

You've dealt with boilers, chillers and the like, I bet. Just saw the HVAC part............

 

[AKDrifter]

Ever seen a steam boiler go?
I used to collect and restore antique tractors, still have most of my antique engines. Because once there's a teeny little gap for the pressure to release through, the water boils instantly (well, pretty much) and it explodes. You take a cap off a HOT radiator and you not only have the escaping steam to deal with but now potentially allow that water to boil violently.

The pressure cap - and the fact it's mixed with antifreeze which is also anti-boil - that in itself raises the boiling point to 223 (for 50/50 ethylene glycol mix) Then add the pressure cap to that and it's well over 260.

I used to work on some commercial steam boilers that powered a state run native hospital and the nearby state jail complex. The steam house was in the middle. They were oil fired and in general very finicky boilers. Hourly water checks and all that kind of thing, massive beasts. That place had steam powered coolers always thought it was neat you could use steam for cooling air. I've not seen one explode but the expansion rate of 15psi steam to atmospheric pressure is insane I can't remember the exact number but it's crazy how fast and how much it instantly expands. I'm dealing almost exclusively in hydronic and forced air these days as far as heating. You don't see steam much anywhere anymore except for places that really need the power of it.

 

[ShadowsPapa]

I used to work on some commercial steam boilers that powered a state run native hospital and the nearby state jail complex. The steam house was in the middle. They were oil fired and in general very finicky boilers. Hourly water checks and all that kind of thing, massive beasts. That place had steam powered coolers always thought it was neat you could use steam for cooling air. I've not seen one explode but the expansion rate of 15psi steam to atmospheric pressure is insane I can't remember the exact number but it's crazy how fast and how much it instantly expands. I'm dealing almost exclusively in hydronic and forced air these days as far as heating. You don't see steam much anywhere anymore except for places that really need the power of it.

Last system I was responsible for was a head trauma facility in Ankeny. At the time I started the building wasn't completed (1990-91) so I was working and learning as the building was being completed (still have my hard hat from those days).
They had 34 heat pumps, a chiller tower outside and a multi-stage electric boiler in the equipment room.
There were a lot of safeties built into that system, but I still recalled the images of steam tractors with old boilers....... so had respect for it.

Anyway, for the onlookers -
ice, like any solid substance, can be COLDER than 32 degrees (F) so saying ice cooled something down to less than 32 - DUH. The ice could be 25 degrees and in that case the thing that you are trying to cool, IF there was enough mass to the ice, the item could be under 32 with ease. No brainer, not rocket science. Water freezes at 32 (not under all conditions, though!) but ice itself, the frozen water, is now a solid so can be cooled below 32 degrees. Ice in a deep freeze is well below 32 degrees meaning you have to warm the ice up to 32 before it melts (under normal conditions)

While water normally boils at 212 (at sea level atmospheric conditions and air pressure) under pressure the boiling point rises - a lot - so water can easily be over 212 - even over 240 and higher under the right conditions - but man, don't let the pressure off! BOOM!

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