Wind Chill Index
The cooling or "chilled" temperature of air in movement - the wind chill index
Sponsored Links
The convective heat loss due to wind can be dramatic. In the table below the wind chill effect is illustrated for air velocities up to 10 m/s (2000 ft/min), or "fresh breeze" according the Beaufort wind scale.
| Air velocity | 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 | 1,000 | 7 | 13 |
| 8 | 1,575 | 8 | 15 |
| 10 | 2,000 | 9 | 16 |
Wind Chill Index - Wind Velocity km/h and degrees Celsius
The "Chilled" air temperature can also be expressed as a function of wind velocity and ambient air temperature as
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 velocity (km/h)
| "Chilled" Air Temperature (oC) | ||||||||
| Ambient Air Temperature (oC) | Wind Velocity (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
Wind Chill Index - Wind Velocity mph and 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 velocity (mph)
| "Chilled" Air Temperature (oF) | ||||||||
| Ambient Air Temperature (oF) | Wind Velocity (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 |
Sponsored Links
Sponsored Links
SketchUp Engineering ToolBox - Online 3D modeling!
SketchUp Engineering ToolBox - enabled for use with the amazing, fun and free Google SketchUp.
Search the ToolBox
© The Engineering ToolBox 2005
8 5 9
