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I though windchill meant temp minus the windspeed? Not according to the readings on weather underground temp 23deg wind speed 7mph windchill 14deg. what gives?

Next question does windchill only effect people or does it affect inantimate objects such as a snowmobile engine? I'm in an arguement with a guy at work who things if if's 10deg out a car engine is under the same stress as if it was 10 deg out with a 30 mph wind. What about for lakes freezing. does it matter what the windchill is or just the actual temp.

I know stupid questions!

Thanks.
 

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Monosodium Glutamate
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what is windchill : windchill (noun), pronounced wind.chill. : a still-air temperature that would have the same cooling effect on exposed human skin as a given combination of temperature and wind speed -- called also chill factor, windchill factor, windchill index

The internet is a wonderful this.
 

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I almost got kicked out of high school after argueing with my science teacher about two northern issues.
One was winchill, he swears scientifically that winchill only affects living things. Anyone who lives north of 60 know this is BS. Park your 06 chev, Ram whatever nose into the wind, lets say its a blamy YK day at -32c and thirty km winds screaming into the rad across a lake, do you think now that windchill will not affect a vehicle, it deffiantely will and that truck won't start. But park in the bush out of the wind an my Dodge will start up to -42 with out being plugged in.
Then the numduts bio teacher was trying to tell the class squirrels are the only true hibernators...this on a morning I was feeding them in the dead of winter at -40 every morning.
So yes windchill affects everything. Ask the boyz in Alaska!
 

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planes take off against the wind
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GTX SPORT 600 HO said:
Windchill only pertains to warm living creatures such as humans and other animals.
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simply put wind chill is the added cooling effect on an object (any object but more often as pertains to living objects) that is created when the wind passes over an object.
If the air is at temp X the wind chill temp is (X-wind speed factor). This factor is the ability of the moving air molecules to absorb heat energy from the object it passes over. Same principle as blowing on something hot to cool it down faster than letting it sit and cool on its own. Scientifically I believe its called Heat transfer by Convection.
We tend to identify it with living objects as they are more effected by this phenomemom (an added point is that moving air absorbs more moisture than sationary air and since we, being a living object are made of water, we loose moisture faster (windburn) which makes the effects of wind chill more significate.

BUT - all matter can be effected by windchill heat loose. We tend not to think in those terms since the vast majority of us do not live where it is significate enough to have a detrimental effect on objects such as cars & trucks....
Which is why my students (you must be if you are still here reading...) you see big trucks with the radiator grilles blocked or restricted in the winter.

Class Dismissed!!!
 

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zdooman said:
GTX SPORT 600 HO said:
Windchill only pertains to warm living creatures such as humans and other animals.
[snapback]705434[/snapback]​
simply put wind chill is the added cooling effect on an object (any object but more often as pertains to living objects) that is created when the wind passes over an object.
If the air is at temp X the wind chill temp is (X-wind speed factor). This factor is the ability of the moving air molecules to absorb heat energy from the object it passes over. Same principle as blowing on something hot to cool it down faster than letting it sit and cool on its own. Scientifically I believe its called Heat transfer by Convection.
We tend to identify it with living objects as they are more effected by this phenomemom (an added point is that moving air absorbs more moisture than sationary air and since we, being a living object are made of water, we loose moisture faster (windburn) which makes the effects of wind chill more significate.

BUT - all matter can be effected by windchill heat loose. We tend not to think in those terms since the vast majority of us do not live where it is significate enough to have a detrimental effect on objects such as cars & trucks....
Which is why my students (you must be if you are still here reading...) you see big trucks with the radiator grilles blocked or restricted in the winter.

Class Dismissed!!!
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Ahem!

Wind chill, will not affect inatimate objects such as steel , except to have a faster cooling effect back down to the ambient air temperature. Wind chill WILL affect any living object because of the cooling down effect of the moisture that all of us release.

Your vehicle's cooling system at -42C is almost a frozen block of ice, not only coolant, but also your oil. If your engine had no oil or coolant , then it would start, but wouldn't run long due to lack of lubrication and cooling.

There are numerous sites on the internet to explain this further. Feel free to peruse them. Then you will come to the understanding of "Wind Chill". OR, just come visit us in Thompson Manitoba, and you can experience it first hand.




 

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How does windchill work...

Have you every riden across a lake a 80 + mph with a leak in your facemask? Or you forgot to zip up your jacket all the way?

That's windchill. Here in Yellowknife...most will tell ya that they would prefer a -30 day with no wind than a -20 day with wind.

No your car does not feel the effects of windchill. Hang a thermometer out your window and drive 60 MPH down the highway and it will still only read the ambient temperature. Windchill cannot be measured with an instrument. Windchill is just how cold it FEELS to the flesh not the ACTUAL temperature.
 

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Just Killin' Time Till Summer
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As stated wind chill will only affect an inanimate object till it cools to ambient temperature.

A quick example is say it's just a degree or two above freezing and raining
Your bombing down the highway at 90 KPH now stick your hand out the window and you get the feeling of -9 Deg Celcius
However your vehicle does not feel this extra cooling or the rain would form Ice on your car windshield grill ECT.
 

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Wind moveing over an object that is heated above ambiant air temperature will remove the excess heat faster than still air. But only down to the ambiant temp. This is the same phenomenon that makes a person feel colder in a breeze than in still air. The wind is removeing your heat faster.

The wind also evaporates water from your body. Evaporation (turning liquid to vapor) absorbs heat, also adding to the feeling of cold. If you have played with the butane refill can, you know how cold it feels to get the liquid butane on you and then have it evaporate. Same pricipal used in car AC and your refrigerator.

Windchill is a subjective number meant to represent what the temp feels like because of the wind.
 

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You know, if you are using a block heater (and I bet you do) the wind will make it harder to keep heat in the engine. That could be the deal here!
 

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Party Chief said:
Wind moveing over an object that is heated above ambiant air temperature will remove the excess heat faster than still air. But only down to the ambiant temp. This is the same phenomenon that makes a person feel colder in a breeze than in still air. The wind is removeing your heat faster.

The wind also evaporates water from your body. Evaporation (turning liquid to vapor) absorbs heat, also adding to the feeling of cold. If you have played with the butane refill can, you know how cold it feels to get the liquid butane on you and then have it evaporate. Same pricipal used in car AC and your refrigerator.

Windchill is a subjective number meant to represent what the temp feels like because of the wind.
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Works the same in summer. Ambient temp and your feeling pretty hot, a breeze comes along that is the same temp and you feel cooler. The wind aids in evaporating the sweat, thus it helps you feel cooler.
 

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Side question, at what temp does metal become brittle. I have worked in northern Quebec at -55 C (static temp) building exploration camps and we brooke some of the tools we were using (wrench, pliers) they seem to snap relatively easily because of the cold... BTW the only snowmobiles that were starting at thos temps were skandic 550 suv's with amsoil, turn the key and let'em heat up for 15 min.
 

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planes take off against the wind
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Party Chief said:
You know, if you are using a block heater (and I bet you do) the wind will make it harder to keep heat in the engine. That could be the deal here!
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This and the prior post is samples of what I mean.

We (living objects) are impacted by windchill in 2 ways:
The faster cooling effect due to the airflow drawing away the heat.
The cooling effect caused by moisture loss associated to the air flow.

Machines are impacted by windchill.
In that they suffer increased heat loss, the faster cool down caused by the airflow.

Revagade - I think you found the abo****e low temps for operating tools... Ever had a hammer shatter?
The exact temp for any given metal object depends on the grade of alloy and heat treating it has been subjected to. So it varies...

Frozegade - How long have you lived there? (j/k)
Your right , you cannot measure wind chill with a thermometer. As I said there are 2 aspects to it from a human perspective. BUT, and most of us will never see it, machines are effected by it, expecially in extreme cases. Heat loss cannot be measured with a thermometer.
And to throw more fuel on this fire. In special cases the temp can get below the ambient temp. Through the use of air flow vectors you can get the temp of an object below the ambient temp. It is not normal but is possible. For those that are mechanics - go see you SnapON, Matco dealers and ask to see a device for testing the old fashioned mechanical choke mechanisms. This device with NO moving parts, can both create hot and cold air. It uses compressed air through the use of controling the air flow vectors and generates hot air at one end and cold air at the other... A neat device.
 

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in the summer, on a really hot day, jump on a motorcycle. it actually feels hotter (if above body temp) becasue there is more warm air blowing across your skin. it works both ways.

More molicules causes the temp to inclrease or decrease faster untill ambient temp is reached. However, putting a fan in your bedroom does not cause the temp to change!
 

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zdooman said:
Party Chief said:
You know, if you are using a block heater (and I bet you do) the wind will make it harder to keep heat in the engine. That could be the deal here!
[snapback]705877[/snapback]​
This and the prior post is samples of what I mean.

We (living objects) are impacted by windchill in 2 ways:
The faster cooling effect due to the airflow drawing away the heat.
The cooling effect caused by moisture loss associated to the air flow.

Machines are impacted by windchill.
In that they suffer increased heat loss, the faster cool down caused by the airflow.

Revagade - I think you found the abo****e low temps for operating tools... Ever had a hammer shatter?
The exact temp for any given metal object depends on the grade of alloy and heat treating it has been subjected to. So it varies...

Frozegade - How long have you lived there? (j/k)
Your right , you cannot measure wind chill with a thermometer. As I said there are 2 aspects to it from a human perspective. BUT, and most of us will never see it, machines are effected by it, expecially in extreme cases. Heat loss cannot be measured with a thermometer.
And to throw more fuel on this fire. In special cases the temp can get below the ambient temp. Through the use of air flow vectors you can get the temp of an object below the ambient temp. It is not normal but is possible. For those that are mechanics - go see you SnapON, Matco dealers and ask to see a device for testing the old fashioned mechanical choke mechanisms. This device with NO moving parts, can both create hot and cold air. It uses compressed air through the use of controling the air flow vectors and generates hot air at one end and cold air at the other... A neat device.
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I have never seen the tool you are talking about, but I would assume it uses a venturi to cool the air.

The venturi effect is caused when airflow is necked down through an orifice, then allowed to expand back to the original condition. This causes the air to flow at an increased velocity through the venturi. As the air expandes it absorbs heat. This and the atomization of fuel (evaporation) which is also absorbing heat, can cause a carburator to ice up at temps above freezing.

This begs another question. What is in an intake manifold, vacuum or pressure?
 

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Party Chief said:
I have never seen the tool you are talking about, but I would assume it uses a venturi to cool the air.

The venturi effect is caused when airflow is necked down through an orifice, then allowed to expand back to the original condition. This causes the air to flow at an increased velocity through the venturi. As the air expandes it absorbs heat. This and the atomization of fuel (evaporation) which is also absorbing heat, can cause a carburator to ice up at temps above freezing.

This begs another question. What is in an intake manifold, vacuum or pressure?
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I have thought about taking it apart to understand it but.... (we all know what happens when you take something apart that works...)
I am sure it is based with the verturi principles but there is more too it. It will move allot of air and during high humidity days it will blow snow.

I think your question is relative. Wether something is in a vacuum or pressure state depends on what it is being compared with. Non-turbo/superchager engines are thought of in vacuum terms. Amount varies with throttle position, load and RPM.
 
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