|
Frostbite Times
|
| 30 minutes |
| 10 minutes |
| 5 minutes |
|
I am more of a cold weather person than a hot weather person. However, cold does tend to slow down the movement of
my fingers, so working outside without gloves is very challenging. This information is derived from
NOAA. Here is a
heat index chart.In 2001, NWS implemented an updated Windchill
Temperature (WCT) index (see table below). NOAA provides the following equation for calculating wind
chill: Wind Chill (°F) = 35.74 + 0.6215T - 35.75(V0.16) +
0.4275(V0.16), where T = Air Temperature (°F), V = Wind Speed
(mph)
| |
40 |
35 |
30 |
25 |
20 |
15 |
10 |
5 |
0 |
-5 |
-10 |
-15 |
-20 |
-25 |
-30 |
-35 |
40 |
| 5 |
36 |
31 |
25 |
19 |
13 |
7 |
1 |
-5 |
-11 |
-16 |
-22 |
-28 |
-34 |
-40 |
-46 |
-52 |
-57 |
| 10 |
34 |
27 |
21 |
15 |
9 |
3 |
-4 |
-10 |
-16 |
-22 |
-28 |
-35 |
-41 |
-47 |
-53 |
-59 |
-66 |
| 15 |
32 |
25 |
19 |
13 |
6 |
0 |
-7 |
-13 |
-19 |
-26 |
-32 |
-39 |
-45 |
-51 |
-58 |
-64 |
-71 |
| 20 |
30 |
24 |
17 |
11 |
4 |
-2 |
-9 |
-15 |
-22 |
-29 |
-35 |
-42 |
-48 |
-55 |
-61 |
-68 |
-74 |
| 25 |
29 |
23 |
16 |
9 |
3 |
-4 |
-11 |
-17 |
-24 |
-31 |
-37 |
-44 |
-51 |
-58 |
-64 |
-71 |
-78 |
| 30 |
28 |
22 |
15 |
8 |
1 |
-5 |
-12 |
-19 |
-26 |
-33 |
-39 |
-46 |
-53 |
-60 |
-67 |
-73 |
-80 |
| 35 |
28 |
21 |
14 |
7 |
0 |
-7 |
-14 |
-21 |
-27 |
-34 |
-41 |
-48 |
-55 |
-62 |
-69 |
-76 |
-82 |
| 40 |
27 |
20 |
13 |
6 |
-1 |
-8 |
-15 |
-22 |
-29 |
-36 |
-43 |
-50 |
-57 |
-64 |
-71 |
-78 |
-84 |
| 45 |
26 |
19 |
12 |
5 |
-2 |
-9 |
-16 |
-23 |
-30 |
-37 |
-44 |
-51 |
-58 |
-65 |
-72 |
-79 |
-86 |
| 50 |
26 |
19 |
12 |
4 |
-3 |
-10 |
-17 |
-24 |
-31 |
-38 |
-45 |
-52 |
-60 |
-67 |
-73 |
-81 |
-88 |
| 55 |
25 |
18 |
11 |
4 |
-3 |
-11 |
-18 |
-25 |
-32 |
-39 |
-46 |
-54 |
-61 |
-68 |
-75 |
-82 |
-89 |
| 60 |
25 |
17 |
10 |
3 |
-4 |
-11 |
-19 |
-26 |
-33 |
-40 |
-48 |
-55 |
-62 |
-69 |
-76 |
-84 |
-91 |
Note: Even NOAA uses both "windchill" and "wind chill" on their website, so the two forms appear to
be interchangeable. Clinical trials were conducted at the Defence and Civil Institute of Environmental
Medicine in Toronto, Canada, and the trial results were used to improve the accuracy of the new formula and
determine frostbite threshold values. Standardization of the WCT Index among the meteorological community provides
an accurate and consistent measure to ensure public safety. The new wind chill formula is now being used in Canada
and the United States.
Specifically, the new WCT index:
- Calculates wind speed at an average height of five feet (typical height of an adult human face) based on
readings from the national standard height of 33 feet (typical height of an anemometer)
- Is based on a human face model
- Incorporates modern heat transfer theory (heat loss from the body to its surroundings, during cold and
breezy/windy days)
- Lowers the calm wind threshold to 3 mph
- Uses a consistent standard for skin tissue resistance
- Assumes no impact from the sun (i.e., clear night sky)
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