wind chill is heat transfer by?

wakejosh

convection right?

OlderDan

I think that is only part of it. Convection keeps the ambient air temperature from rising. It takes more than that to make you feel cold.

QuantumCrash

Convection would be more associated with the production of the wind itself than actual chill.

EthanB

When the wind blows against your skin, you interact with more air molecules, transferring more heat. That's why the wind chill factor is an apparent temperature change; the temperature is the same, but heat is conducted away from you more quickly. Kind of like how a hot tub at 100 degrees feels much hotter than air at 100 degrees. Same temperature, different conductivity.

wakejosh

so would it be Conduction instead of Convection? I dont have the right version of the book and I cant figure out what he wants here for the life of me. my only options are conduction, convection, and radiation.

EthanB

I'm not entirely sure. I want to say convection...

OlderDan

Convection is what changes for wind compared to no wind, but if there were no conduction it would not make any difference. If your skin were a perfect insulator, you would feel no difference when the wind blows. When the air is still, a layer of warm air builds up around you. Clothing provides a region of captured warm air that keeps you reasonably comfortable on cold days. If you take that layer of warm air away, your body loses heat faster by conduction to the cold air. Of course there is all kinds of convection going on inside your body as well, with blood flowing through your extremities.

DaveC426913

I think the point here is that, technically, ALL heat transfer from one medium to an adjacent medium involves conduction. If not, there would be zero transfer from your skin to the air.

Then again, if conduction were ALL there was to it, then the air around you would warm up and keep you blanketed in a layer of warm air.

Convection is the process whereby that warm air is carried away, drawing cool air next to your skin where it can continue to draw more heat off.

So, while there is conduction occurring, the primary cause of heat loss is convection.