Wind Chill and Frostbite


by BradP
Tags: chill, frostbite, wind
BradP
BradP is offline
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Jun26-12, 09:48 PM
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Two questions. I have read that wind chill is a measurement (or calculation, more accurately) that describes how cold the wind feels, even though the wind isn't actually colder than still air. What I am wondering is why isn't the wind actually colder? If it is moving faster it is lower pressure than the surrounding air, and thus according to the ideal gas law also lower temperature, right?

Secondly I have read on a few different sources that you can get frostbite above freezing temperatures if there is a strong wind chill. How can that be? Doesn't frostbite only happen when the skin or blood vessels freeze? I did not think it was possible for heat to flow from lower temperature body to higher temperature body.
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haruspex
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Jun27-12, 01:39 AM
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Quote Quote by BradP View Post
If it is moving faster it is lower pressure than the surrounding air
I don't see why. This is not in a venturi tube. In fact, if you held a tube open at both ends transverse to the wind I think you'd find the pressure in the tube would be lower.
Secondly I have read on a few different sources that you can get frostbite above freezing temperatures if there is a strong wind chill. How can that be? Doesn't frostbite only happen when the skin or blood vessels freeze? I did not think it was possible for heat to flow from lower temperature body to higher temperature body.
I agree with you - I don't see how this can be true.
This NOAA site http://www.nws.noaa.gov/os/windchill...ry.shtml#frost is a bit confusing, but it does say clearly:Object will NOT cool below the actual air temperature.


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