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convert/windchill

convert temperature-speed pairs to windchill

 Calling Sequence convert([t, s], windchill, [ut, us], opts) convert([t*Unit(ut), s*Unit(us)], windchill, opts)

Parameters

 t - temperature s - wind speed ut - units of temperature us - units of wind speed opts - equation options as described below

Options

 • formula : one of OsczevskiBluestein or SiplePassel (see description); default is OsczevskiBluestein.

Description

 • The convert([t, s], windchill, [ut, us]) function converts the temperature-speed pair $t,s$ to the corresponding windchill factor corresponding to the units of temperature ut.
 • The convert([t*Unit(ut), s*Unit(us)], windchill ) function is similar to the first calling sequence.
 • The formula used by the U.S. National Weather Service and Environment Canada is

$35.74+0.6215T-35.75{V}^{0.16}+0.4275T{V}^{0.16}$

 where T is the temperature in degrees Fahrenheit, and V is the wind velocity in miles per hour.  The result is the apparent temperature in degrees Fahrenheit.
 • The above formula was developed in 2001 by the Joint Action Group for Temperature Indices (see Osczevski and Bluestein).
 • This calculation is intended as an approximation. It is used only for wind speeds between 4 mph ( $6\frac{\mathrm{km}}{h}$ ) and 50 mph ( $80\frac{\mathrm{km}}{h}$ ).
 • The above Osczevski-Bluestein formula replaces an earlier formula for windchill due to Siple and Passel:

$91.4+\left(0.474677-0.020425V+0.303107\sqrt{V}\right)\left(T-91.4\right)$

 in which the variables are defined as in the previous formula.
 Windchill computations using the Siple-Passel formula are possible by adding the option formula=SiplePassel in the call to convert.

Examples

Determine the apparent temperature with a temperature of 37°F and wind velocity of 10 mph.

 > $\mathrm{convert}\left(\left[37,10\right],\mathrm{windchill},\left[\mathrm{degF},\mathrm{mph}\right]\right)$
 ${29.92427177}$ (1)

Compare this result to the result using historical Siple-Passel formula for wind chill.

 > $\mathrm{convert}\left(\left[37,10\right],\mathrm{windchill},\left[\mathrm{degF},\mathrm{mph}\right],\mathrm{formula}=\mathrm{SiplePassel}\right)$
 ${24.54590909}$ (2)

Determine the apparent temperature with a temperature of 3°C and wind velocity of 16 km/h.

 > $\mathrm{convert}\left(\left[3,16\right],\mathrm{windchill},\left[\mathrm{degC},\frac{\mathrm{km}}{h}\right]\right)$
 ${-0.8629766}$ (3)

Convert the resulting temperature from Celsius to Fahrenheit.

 > $\mathrm{convert}\left(,\mathrm{temperature},\mathrm{degC},\mathrm{degF}\right)$
 ${30.4466421}$ (4)

References

 Osczevski, Randall, Maurice Bluestein, 2005: The New Wind Chill Equivalent Temperature Chart. Bulletin of the American Meteorological Society, 86, 1453–1458. doi: http://dx.doi.org/10.1175/BAMS-86-10-1453

 See Also