Wind Chill Numbers...

[Byrdman]

OK, this is not so new, but I had not heard about it… Fell upon this just checking to see what the wind chill would have been on the lake Saturday…. I had an old chart that indicated that ice should have been forming at least in the splash areas… and none was to be found… so, I thought I’d research a little bit and look what I found….
Old Chart = 42 w/ 17 mph wind = 23 degrees.....at least ice in splash areas but none
New Chart = 42 w/ 17 mph wind = 34 degrees.....and no ice.... just like it was on the lake...

I was about to get my glasses checked again thinking I could not read my old chart...or.... find me a larger print chart.... and whammmy
Check it out.
http://www.crh.noaa.gov/dmx/0winter/new_windchill.html#New

[CAVU]

Byrdman, if the air temp is 42, I don't think ice would form if the wind blew 100 kts. As I understand it wind chill only applies to unprotected skin?

[Chuck S]

Like they say on the weather report wind chill feels like a lower temperature.

-- Chuck

[Sea Wolf]

Right, Ken! The Wind Chill Temperature is an attempt to relate actual temperature and the moving winds effect on bare skin to give an equivalent temperature that would cause the same chilling without that wind. Even though the wind chill factor might say its equivalent to 20 degrees outside, the water will not freeze until the actual temperature reaches 32 degrees Fahrenheit, or 0 degrees Celsius, period! And even then a lot of heat has to be taken out of each bit of water to change it from water at that temperature to ice at that same temperature. (I'll avoid the science lesson here for sake of simplicity).

In a seeming paradox, even in orchards where they're trying to prevent freezing, they use wind machines to circulate the air enough to keep what residual heat there is in the environment into the trees and fruit to avoid this final heat loss that allows water to solidify. Once the whole orchard mass reaches freezing temperatures and still continues to loose heat, however, the freezing begins.

The freezing over of lakes takes a great deal of cooling to take place, and the ice out in spring is an equally energy demanding task, albeit in the opposite direction.

Thanks for the new table/index, Byrdman!

Stay Warm, Dry, and out of the Wind Chill!!! Joe.