Wind Chill Index
Effective Temperature of air in movement.
The convective heat loss due to wind can be dramatic. In the table below the wind chill effect is illustrated for air speeds up to 10 m/s (36 km/h, 2000 ft/min, 22 mph), or "fresh breeze" according the Beaufort wind scale.
| Air Speed | Chill Effect | ||
|---|---|---|---|
| (m/s) | (ft/min) | (oC) | (oF) |
| 0.1 | 20 | 0 | 0 |
| 0.25 | 50 | 0.5 | 2 |
| 1.5 | 300 | 4 | 7 |
| 3 | 600 | 6 | 10.5 |
| 5 | 1000 | 7 | 13 |
| 8 | 1575 | 8 | 15 |
| 10 | 2000 | 9 | 16 |
Wind Chill Index - Wind Speed in km/h and Temperature in degrees Celsius
"Chilled" air temperature can be expressed as a function of wind speed and ambient air temperature
twC = 13.12 + 0.6215 ta - 11.37 v0.16 + 0.3965 ta v0.16 (1)
where
twC = effective "wind" temperature (oC)
ta = air temperature (oC)
v = wind speed (km/h)
| "Chilled" Air Temperature (oC) | ||||||||
|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature (oC) | Wind Speed (km/h) | |||||||
| 5 | 10 | 15 | 20 | 30 | 40 | 50 | 60 | |
| 10 | 10 | 9 | 8 | 7 | 7 | 6 | 5 | 5 |
| 5 | 4 | 3 | 2 | 1 | 0 | -1 | -1 | -2 |
| 0 | -2 | -3 | -4 | -5 | -6 | -7 | -8 | -9 |
| -5 | -7 | -9 | -11 | -12 | -13 | -14 | -15 | -16 |
| -10 | -13 | -15 | -17 | -18 | -20 | -21 | -22 | -23 |
| -15 | -19 | -21 | -23 | -24 | -26 | -27 | -29 | -30 |
| -20 | -24 | -27 | -29 | -30 | -33 | -34 | -35 | -36 |
| -25 | -30 | -33 | -35 | -37 | -39 | -41 | -42 | -43 |
| -30 | -36 | -39 | -41 | -43 | -46 | -48 | -49 | -50 |
| -35 | -41 | -45 | -48 | -49 | -52 | -54 | -56 | -57 |
| -40 | -47 | -51 | -54 | -56 | -59 | -61 | -63 | -64 |
- 1 km/h = 0.2778 m/s = 54.68 ft/min = 0.6214 mph = 0.5396 knot
Download and print Wind Chill Index chart
Wind Chill Index - Wind Speed in mph and Temperature in degrees Fahrenheit
The "Chilled" air temperature can also be expressed as a function of wind velocity and ambient air temperature as
twF = 35.74 + 0.6215 ta - 35.75 v0.16 + 0.4275 ta v0.16 (2)
where
twF = effective temperature (oF)
ta = air temperature (oF)
v = wind speed (mph)
| "Chilled" Air Temperature (oF) | ||||||||
|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature (oF) | Wind Speed (mph) | |||||||
| 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | |
| 40 | 36 | 34 | 32 | 30 | 29 | 28 | 28 | 27 |
| 35 | 31 | 27 | 25 | 24 | 23 | 21 | 21 | 20 |
| 30 | 25 | 21 | 19 | 17 | 16 | 14 | 14 | 13 |
| 25 | 19 | 15 | 13 | 11 | 9 | 7 | 7 | 6 |
| 20 | 13 | 9 | 6 | 4 | 3 | 0 | 0 | -1 |
| 15 | 7 | 3 | 0 | -2 | -4 | -7 | -7 | -8 |
| 10 | 1 | -4 | -7 | -9 | -11 | -14 | -14 | -15 |
| 5 | -5 | -10 | -13 | -15 | -17 | -21 | -21 | -22 |
| 0 | -11 | -16 | -19 | -22 | -24 | -27 | -27 | -29 |
| -5 | -16 | -22 | -26 | -29 | -31 | -37 | -34 | -36 |
| -10 | -22 | -28 | -32 | -35 | -37 | -41 | -41 | -43 |
| -15 | -28 | -35 | -39 | -42 | -44 | -48 | -48 | -50 |
| -20 | -34 | -41 | -45 | -48 | -51 | -55 | -55 | -57 |
| -25 | -40 | -47 | -51 | -55 | -58 | -62 | -62 | -64 |
| -30 | -46 | -53 | -58 | -61 | -64 | -69 | -69 | -71 |
| -35 | -52 | -59 | -64 | -68 | -71 | -76 | -76 | -78 |
| -40 | -57 | -66 | -71 | -74 | -78 | -82 | -82 | -84 |
Download and print Wind Chill Index chart
| Wind Chill | Possible Effects |
|---|---|
| 30oF or higher | Generally unpleasant |
| 30o to 15oF | Unpleasant |
| 14o to 0oF | Very unpleasant |
| -1o to -20oF | Frostbite possible |
| -21o to -60oF | Frostbite likely - outdoor activities dangerous |
| -61o or lower | Exposed flesh freezes within 30 seconds |
Related Topics
-
Environment
Climate, meteorology, sun, wind and environmental related engineering resources. -
Physiology
Human physiology, air quality and comfort temperatures, activity and metabolic rates, health effects of carbon monoxide and more.
Related Documents
-
Beaufort's Wind Scale
The Beaufort description and observation scale for wind and wind speed. -
Convective Heat Transfer
Heat transfer between a solid and a moving fluid is called convection. This is a short tutorial about convective heat transfer. -
Fujita-Pearson Tornado Intensity Scale
A tornado intensity rating scale. -
Hurricane Intensity Scale
The Saffir-Simpson hurricane damage potential scale. -
Survival Time in Cold Water
Time to exhaustion and death for humans in cold water. -
Wind Load vs. Wind Speed
Wind load on surface - Wind load calculator.
