Wind Chill factor

[TXiceman]

I just wanted to post the following to clear up a fairly common misconception.

Please see the following article on Wind Chill.

WIND CHILL.

It can be 33 degF outside and a Wind Chill temperature of 25 degF. Will you pipes or radiator freeze?


NOPE. All the pipes see is the 33 degF temperature.

Wind Chill is an apparent temperature live tissue feels due to the evaporation of the moisture in the skin. You can easily demonstrate this effect for your self. Wet your finger and wave it around in the air....it feels cooler doesn't it.

Ken

[Ray,IN]

Right on Ken! I've even had a Dutchmen service tech, tell me the wind-chill while driving would freeze my RV plumbing. I never bothered to correct him., just walked away.

[haulinhazmat]

Wind chill is a term made up by some weather person so he would have a new word to use. Wind chill won't freeze water. I drove a truck and pulled a tanker and we had to record a temperture reading and a pressure reading every 2 hours.the gauage was mounted on the tankers fender. Setting still or moving at 60 mph the temperture didn't change from ambient.

[ksg5000]

My recollection is that wind chill effects how quickly heat leaves an object - but it can't go below the actual outside temperature. If I am correct then wind chill does affect inanimate objects it just doesn't lower the actual point of freezing.

[historyljc]

Quote:

Originally Posted by TXiceman I just wanted to post the following to clear up a fairly common misconception. Please see the following article on Wind Chill. WIND CHILL. It can be 33 degF outside and a Wind Chill temperature of 25 degF. Will you pipes or radiator freeze? NOPE. All the pipes see is the 33 degF temperature. Wind Chill is an apparent temperature live tissue feels due to the evaporation of the moisture in the skin. You can easily demonstrate this effect for your self. Wet your finger and wave it around in the air....it feels cooler doesn't it. Ken

Now if I could just convince my wife of that.

[TXiceman]

Quote:

Originally Posted by ksg5000 My recollection is that wind chill effects how quickly heat leaves an object - but it can't go below the actual outside temperature. If I am correct then wind chill does affect inanimate objects it just doesn't lower the actual point of freezing.

ksg5000, read the article linked in the first post. It explains it pretty well and it is nothing like your thinking.....

Ken

[wildtoad]

Actually the article supports KSG5000's thought. The following was copied directly from the article.

"For inanimate objects, the effect of wind chill is to reduce any warmer objects to the ambient temperature more quickly. It cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity."

The cold air moving over a warm object will cause the object to cool more rapidly than if the air was calm. This is the basic way radiators work.

[TXiceman]

Quote:

Originally Posted by wildtoad The cold air moving over a warm object will cause the object to cool more rapidly than if the air was calm. This is the basic way radiators work.

What they are talking about here is the heat transfer rate or heat transfer coefficient (Uo). I guess in trying to keep it simple, they used "wind chill" as a simplified approach and not introduce another term. The higher velocity across the surface increases the Uo and thus more heat is pulled from the surface. You can increase the velocity to the point that the Uo starts to decrease and reduces the heat transfer rate. Still this is not truly wind chill.

I tried to find the simplest article for explaining this effect. I have been working with heat transfer and thermodynamics since 1970 and some of the concepts can be hard to explain and comprehend in layman terms.

Ken

[wildtoad]

I agree that using "wind chill" for pipes etc is not accurate. I think it is safe to say that a cold blowing wind on that pipe will result in lowering the temp of the pipe to the true outside temp faster.

Thanks for the orig post btw.

Tom

[Wayne M]

Ken,
I have known for some time that "wind chill" does not have an effect on inanimate objects - therefore you should remain warm.

However, as stated "wind chill" (coefficient) is changed on inanimate objects by the introduction of a breeze. Call it what you want, but if you have a spoon full of hot food and blow on it, it will cool down sufficiently faster than just letting it sit there. (Well, not in your case.) As stated, it will not fall below ambient temperature.

I know Jim is ROFLHAO.

[StStg1]

Ken,

Just wanted to say thanks for posting a very informative article.

[two-niner]

Wind chill, according to the Mechanical Code (HVAC), is the temperature your body perceives it to be. Pretty simple, no icing on the wings.

Kerry

[TXiceman]

Wayne, I am only inanimate when I have a cold beer or a glass of George Dickel.

Ken

[Ray,IN]

Wind Chill or perceived temperature is exactly why the Military uses the "wet bulb thermometer". It works both ways, when it is cold, or hot, outside. We used wet bulb thermometers to tell us exactly what temperature the trainees bodies were experiencing during outside training.