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Overview :
Prolonged
exposure to severe cold can result in hypothermia and/or tissue necrosis. It is
important to keep the core body temperature from falling below 96.8 degrees
Fahrenheit, and to prevent cold injury to the extremities or exposed body
parts.
As the wind
speed increases, there is an additional cooling effect, decreasing the effective
temperature to the exposed individual. The effect increases until wind speeds
reach 40 miles per hour, after which there is little additional effect. Tissue
freezing will occur only at temperatures below 30.2 degrees Fahrenheit,
regardless of wind speed. The presence of wetting greatly increases the risk for
hypothermia and must be aggressively prevented.
Table of Effective Temperature
Experienced for a Given
Temperature in °F and Wind Speed in miles
per hour
|
Windmph |
50 °F |
40 °F |
30 °F |
20 °F |
10 °F |
0 °F |
-10 °F |
-20 °F |
-30 °F |
-40 °F |
-50 °F |
-60
°F |
|
0 |
50 |
40 |
30 |
20 |
10 |
0 |
-10 |
-20 |
-30 |
-40 |
-50 |
-60 |
|
5 |
48 |
37 |
27 |
16 |
6 |
-5 |
-15 |
-26 |
-36 |
-47 |
-57 |
-68 |
|
10 |
40 |
28 |
16 |
4 |
-9 |
-24 |
-33 |
-46 |
-58 |
-70 |
-83 |
-95 |
|
15 |
36 |
22 |
9 |
-5 |
-18 |
-32 |
-45 |
-58 |
-72 |
-85 |
-99 |
-112 |
|
20 |
32 |
18 |
4 |
-10 |
-25 |
-39 |
-53 |
-67 |
-82 |
-96 |
-110 |
-121 |
|
25 |
30 |
16 |
0 |
-15 |
-29 |
-44 |
-59 |
-74 |
-88 |
-104 |
-118 |
-133 |
|
30 |
28 |
13 |
-2 |
-18 |
-33 |
-48 |
-63 |
-79 |
-94 |
-109 |
-125 |
-140 |
|
35 |
27 |
11 |
-4 |
-20 |
-35 |
-51 |
-67 |
-82 |
-98 |
-113 |
-129 |
-145 |
|
40+ |
26 |
10 |
-6 |
-21 |
-37 |
-53 |
-69 |
-85 |
-100 |
-116 |
-132 |
-148 |
Equation with Wind Speed
Constant
effective
temperature in °F at a given wind speed in miles per hour
=
= (a *
(temperature)) + b
|
wind speed in
mph |
a |
b |
|
0 |
1 |
0 |
|
5 |
1.051049 |
-4.744755 |
|
10 |
1.2293706 |
-21.35315 |
|
15 |
1.3437063 |
-31.53147 |
|
20 |
1.4108392 |
-38.6958 |
|
25 |
1.4832168 |
-44.08392 |
|
30 |
1.5286713 |
-48.18998 |
|
35 |
1.5601399 |
-51.03263 |
|
40 |
1.5793706 |
-53.01981 |
Equation with External Temperature
Constant
wind speed < 10 miles per
hour
effective
temperature for a given external temperature =
= (a * ((wind speed in mph) ^2)) + (b *
(wind speed in mph)) + c
|
external
temperature |
a |
b |
c |
|
-60 °F |
-0.38 |
0.3 |
-60 |
|
-50 °F |
-0.38 |
0.5 |
-50 |
|
-40 °F |
-0.32 |
0.2 |
-40 |
|
-30 °F |
-0.32 |
0.4 |
-30 |
|
-20 °F |
-0.20 |
0.2 |
-20 |
|
-10 °F |
-0.26 |
0.3 |
-10 |
|
0 °F |
-0.28 |
0.4 |
0 |
|
10 °F |
-0.22 |
0.3 |
10 |
|
20 °F |
-0.16 |
0 |
20 |
|
30 °F |
-0.16 |
0.2 |
30 |
|
40 °F |
-0.12 |
0 |
40 |
|
50 °F |
-0.12 |
0.2 |
50 |
Equation with External Temperature
Constant
wind speed >= 10 miles per
hour
effective
temperature for a given external temperature =
= (a * ((wind
speed in mph) ^3)) + (b * ((wind speed in mph) ^2)) + (c * (wind speed in mph))
+ d
|