Heres what Wikipidia says is current:
North American and United Kingdom wind chill index
In November 2001, Canada, the United States, and the United Kingdom implemented a new wind chill index developed by scientists and medical experts on the Joint Action Group for Temperature Indices (JAG/TI).[5][6][7] It 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; 3.1 mph). The model corrects the officially measured wind speed to the wind speed at face height, assuming the person is in an open field.[8] The results of this model may be approximated, to within one degree, from the following formula:
The standard Wind Chill formula for Environment Canada is:
{\displaystyle T_{\mathrm {wc} }=13.12+0.6215T_{\mathrm {a} }-11.37v^{+0.16}+0.3965T_{\mathrm {a} }v^{+0.16}} {\displaystyle T_{\mathrm {wc} }=13.12+0.6215T_{\mathrm {a} }-11.37v^{+0.16}+0.3965T_{\mathrm {a} }v^{+0.16}}
where Twc is the wind chill index, based on the Celsius temperature scale; Ta is the air temperature in degrees Celsius; and v is the wind speed at 10 m (33 ft) standard anemometer height, in kilometres per hour.[9]
When the temperature is −20 °C (−4 °F) and the wind speed is 5 km/h (3.1 mph), the wind chill index is −24. If the temperature remains at −20 °C and the wind speed increases to 30 km/h (19 mph), the wind chill index falls to −33.
The equivalent formula in US customary units is:[10]
{\displaystyle T_{\mathrm {wc} }=35.74+0.6215T_{\mathrm {a} }-35.75v^{+0.16}+0.4275T_{\mathrm {a} }v^{+0.16}\,\!} {\displaystyle T_{\mathrm {wc} }=35.74+0.6215T_{\mathrm {a} }-35.75v^{+0.16}+0.4275T_{\mathrm {a} }v^{+0.16}\,\!}
where Twc is the wind chill index, based on the Fahrenheit scale; Ta is the air temperature in degrees Fahrenheit, and v is the wind speed in miles per hour.[11]
Windchill temperature is defined only for temperatures at or below 10 °C (50 °F) and wind speeds above 4.8 kilometres per hour (3.0 mph).[10]
As the air temperature falls, the chilling effect of any wind that is present increases. For example, a 16 km/h (9.9 mph) wind will lower the apparent temperature by a wider margin at an air temperature of −20 °C (−4 °F), than a wind of the same speed would if the air temperature were −10 °C (14 °F).
Graph of degrees of wind chill for wind speed and air temperature
Celsius wind chill index
Graph comparing "old" and "new" wind chill values by wind speed at 15°C air temperature
Comparison of old and new wind chill values at −15 °C (5 °F)
Picture of a manual wind chill calculator
Wind chill calculator
The 2001 WCET is a steady state calculation (except for the time to frostbite estimates).[12] There are significant time-dependent aspects to wind chill because cooling is most rapid at the start of any exposure, when the skin is still warm.
Steve Perry wrote:
Wind chill doesn't affect cameras, only people. While wind can help pull the heat from the camera, the camera itself will never be colder than the actual, ambient air temp. Wind chill is simply how it "feels" to a person, camera's don't care.