Can heat from air friction balance out wind chill?

Question

If you have a warm steel sphere approximately the size of a baseball and cause cool air to flow past it - at what velocity will the heat gained by air friction balance with the heat lost to "wind chill" so that the sphere's temperature remains constant?

Answer 1

Guys, don't forget Newton's law of cooling? If you pass air across a surface you can cool something? This is more relevant than wind chill.

You can cool down a steel sphere using air, but you'll only change the temperature by a small amount. Unless you take the steel sphere from an environment from say 22C to -22C and then measure how long it takes for the sphere to reach an ambient temperature of -22C with and without a breeze passing across it.

Typically you are looking at beyond supersonic wind speeds before air friction will come into effect. Remember the heat shields spacecraft need when returning to earth. This is to combat friction arising from air resistance.

Answer 2

"Wind chill" is a combination of conduction and convection. A person sweats and the evaporation phase change that is accelerated by the wind, causes an absorption of heat energy from the skin tissue around the sweat. (conduction). Obviously the ball will not sweat, and therefore this effect can be factored out.

But the wind also increases forced convection which will directly transfer heat away from the ball. Assuming the ball is warm - hotter than the ambient temperature - The ball can be cooled by convection only to the point where the ball and the ambient temperature have become the same value.

Of course, technically it can never be cooled to this exact point because the air temperature is a limit and further the negligible amount of air friction will prevent these two values from ever perfectly coinciding.

Answer 3

Wind chill is felt when air blows over moisture at or near the skin. Makes no difference where that moisture comes from (e.g., sweat, fall in the river). The chill is felt because the air increases the rate of evaporation and the evaporated water draws off heat from the body. That's the chill.

Think about your question. There is clear evidence almost every day that "air friction" can balance out wind chill. That evidence is in shooting stars...meteors.

Air friction is what makes meteors burn up and show up in the night skies. Air friction makes them hot enough to burn up iron, which many meteors have in them. So, we have to conclude, air friction can heat up your own body if it were falling fast enough through the atmosphere. You would not be chilled as you burned up.

On the other hand, I think we've all experienced wind over our bodies that caused wind chill. The friction heat at those much lower velocities is clearly not balanced out...otherwise, we'd not be chilling as the wind blows.

So the answer is clearly, yes heat from air friction can balance out wind chill at some high velocity through the air. It is also clear that the chills are not balanced out at the lower velocities.

Answer 4

"Wind chill" is a phenomenon that is only experienced by things with an active cooling mechanism, such as people. When people sweat, the moisture absorbs heat from their surface (skin) and then evaporates, carrying the heat away. When the wind blows, the heat gets carried away faster, making it "feel" colder. Since the steel sphere would presumably have no such mechanism, there would be no "wind chill".

Answer 5

A steel sphere doesn't perspire, so it doesn't experience windchill. Windchill is the by-product of increase water evaporization from the skin or damp objects because of increased air flow.

Wind chill is substantial for humans, whereas heat due to friction or air resistance is negligible at modest air flow rates.

Answer 6

Steel spheres don't experience wind chill. They don't sweat.

Answer 7

wind is often going to experience slightly less warm to us (till it extremely is already extremely warm) by way of fact it blows away the warmth air surrounding our bodies from our physique warmth. At any temperature the wind reasons some friction, however the blowing away of physique warmth is greater significant.