Wind Chill Index

The cooling or "chilled" temperature of air in movement - the wind chill index

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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

wind chill index celcius diagram

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

wind chill effect velocity mph degrees fahrenheit

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Related Topics

  • Environment Climate, Meteorology, Sun, Wind and environmental resources ..
  • Physiology Human physiology, air quality and comfort temperatures, activity and metabolic rates, health effects of carbon monoxide and more

Related Documents

  • Beaufort Wind Scale Beauforts description and observation of wind and wind velocity
  • Convective Heat Transfer Heat transfer between a solid and a moving fluid is called convection. This is a short tutorial about convective heat transfer

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