Sooo, you think it's cold where you are... (Ellsworth, Hampden: health insurance, Home Depot)

[Northern Maine Land Man]

Chill factor is the rate that a surface will cool to ambient temperature, whether the surface can "feel" or not.

[kellysmith]

Originally Posted by Northern Maine Land Man

Chill factor is the rate that a surface will cool to ambient temperature, whether the surface can "feel" or not.

Fake news...chill factor is caused by heat being removed from an object by evaporation. Skin that is exposed to wind will have water moisture evaporate from it. The evaporation of moisture from our skin removes some heat as well. The higher the wind, the more evaporation, the more heat loss.
Now you can argue than a metal engine will not be affected by wind chill since there will be no water evaporation from it's surface and you will be correct. It is also correct that when the wind is blowing 20 miles an hour at zero degrees, a vehicle seems to start harder. That is because the zero degree air is circulated more efficiently to get the engine to zero degrees. Inanimate objects technically are not affected by wind chill. Exposed skin is, but it's because of evaporation and therefore a cooling of the skin.

[Bailey340]

Originally Posted by kellysmith

Fake news...chill factor is caused by heat being removed from an object by evaporation. Skin that is exposed to wind will have water moisture evaporate from it. The evaporation of moisture from our skin removes some heat as well. The higher the wind, the more evaporation, the more heat loss.
Now you can argue than a metal engine will not be affected by wind chill since there will be no water evaporation from it's surface and you will be correct. It is also correct that when the wind is blowing 20 miles an hour at zero degrees, a vehicle seems to start harder. That is because the zero degree air is circulated more efficiently to get the engine to zero degrees. Inanimate objects technically are not affected by wind chill. Exposed skin is, but it's because of evaporation and therefore a cooling of the skin.

Good explanation. That’s why a thermometer doesn’t go up and down when the wind blows.

[OutdoorLover]

I don't know what meteorologists define as "wind chill factor". But I do know that warmer objects will lose heat faster under windy conditions than in still air, as Northern Maine Land Man suggests, even if there is no evaporation. In still air, the layer of air adjacent to the warm object is warmed as heat is lost by it - that reduces the temperature differential at the interface, slowing heat loss. Under windy conditions, the warmed air is immediately swept away and replaced with cold air, giving maximal heat loss rates.

[Zymer]

Originally Posted by OutdoorLover

I don't know what meteorologists define as "wind chill factor". But I do know that warmer objects will lose heat faster under windy conditions than in still air, as Northern Maine Land Man suggests, even if there is no evaporation. In still air, the layer of air adjacent to the warm object is warmed as heat is lost by it - that reduces the temperature differential at the interface, slowing heat loss. Under windy conditions, the warmed air is immediately swept away and replaced with cold air, giving maximal heat loss rates.

This is true, to an extent, as those of us who ride motorcycles with air-cooled motors are well aware. However, for metal already at ambient temp there is no additional cooling due to wind.

[kevin5098]

According to Wikipedia, wind chill index used by meteorologists in the US "is determined by iterating a model of skin temperature under various wind speeds and temperatures using standard engineering correlations of wind speed and heat transfer rate. Heat transfer was calculated for a bare face in wind, facing the wind, while walking into it at 1.4 metres per second (5.0 km/h)." See the entire article for details.

[Northern Maine Land Man]

I flew helicopters in the Antarctic. We had no heat in those birds. We had no face masks back in 1964 so we made our own. People's faces and hands do not sweat in winter or cold conditions. I grew a beard back in 1964. I shaved it off before we got back up to the equator. The beard was very helpful in reducing chill factor. Out of self defense, I am growing a beard again for the first time since 1964. That wind is brutal when I'm on the Kubota. I don't have a cab, much less a heated cab. I got hand warmers for Christmas. My family reads both farmers almanacs. Both predicted both large storms we had recently. Both predicted a harder winter this year.

[Pincho-toot]

-13 this weekend in St. Paul, MN. That's nothing.. wait til it's -25.

[Kiwiluver]

We didn’t have wind chill, or heat index back in the day. Not sure how we made it.

[UpTheCreek]

Originally Posted by BadgerFilms

-13 this weekend in St. Paul, MN. That's nothing.. wait til it's -25.

It is COLD in Minnesota, that’s a fact! I’ve seen better than -24F at my house this winter, although it’s not nearly as common as many places in Minnesota. I guess my point is that we know what real cold is, we just don’t experience it near as often as you! Thankfully!