Wind chill

For outdoor work there may be a risk of frostbite in the wintertime. The report uses the wind chill temperature, WCI, calculated as... 

TABLE 6.12 Wind Chill Index, WCI, Chilling Temperature, and Effect on Exposed Flesh... 

Wind chill index An empirical scale that correlates well with the sensation of bare dry skin due to the chilling effect of the outdoor air temperature and wind speed. 

WORST 1 No written procedures, or standard way of performing tasks Not integrated with training High levels of noise Poor lighting High or very low temperatures and high humidity or wind chill factors... 

Wind Chill Equivalent Temperatures on Exposed Flesh at Varying Velocity... 

Cold injury (frostbite and hypothermia) and impaired ability to work are dangers at low temperatures and when the wind-chill factor is low. To guard against them, the personnel at an industrial site should (a) wear appropriate clothing, (b) have warm shelter readily available, and (c) carefully schedule work and rest periods, and monitor workers physical conditions. 

But everyone felt much, much colder cos The wind chill index made it minus nine. 

The temperature at the surface of the droplet is determined by the evaporation rate obtained from simultaneous mass and heat transfer equation (8.10). (This temperature is the same as the wind chill factor discussed in weather forecasts, which can be calculated with equation (8.10) assuming the form of a moist sphere the size of the average human head.) Under some drying conditions, the heat transfer is the slow step, limiting evaporation, and in others the mass transfer is the slow step. In either case the evaporation rate, dRJdt, can be written as... 

Figure 5.75. Hourly time variation of low-temperature heat (space heating and hot water) calculated for the 2050 scenario with use of actual temperature and wind chill data for Denmark during the year 1999 (Sorensen et al, 2001).

Fur heal transfer purposes, a standing man can be modeled as a 30 Cm diameier, 170 cm-loag vertical cylinder with both the top and botiom surfaces insulared and with the side surface at an average temperature of 34"C. For a convection heat transfer coefficient of 15 W/m "C, deiemiine the rale of heat loss from ihis man by convection in still air al 20°C. What would your answer be if the convection heal transfer coefficient is Increased to 50 W/m °C as a result of winds What is the wind-chill factor in this case Ansuers 336 W, 11 0 W, 3 .7 C... 

See also Air masses and fronts Atmosphere observation Atmosphere, composition and structure Atmospheric circulation Atmospheric temperature Dew point Fog Greenhouse effect Hydrologic cycle Weather forecasting Weather mapping Weather modification Wind chill Wind shear. 

Elence W decreases only very slowly at wind speeds above 50 mi / h, at least assuming that if not Eq. (14) in its entirety then at least this aspect of Eq. (14) retains at least approximate validity at Neptune-like temperatures. The singularity in (dW/dV)T at V = Omi/h is sufficiently weak that it has no effect on values of W itself.] Since standard atmospheric pressure at sea level on Earth is approximately lbar, for illustrative purposes and for argument s sake let us assume that the standard wind chill formula [Eq. (14)] retains at least approximate validity at the 1 bar level on Neptune, especially since the atmospheric density of 0.45 kg / m3 at the 1 bar level on Neptune is at least comparable to that at the 1 bar level on Earth. (We will appraise this assumption later in this Sect. 4.2, especially in the second-to-last paragraph thereof.) The temperature in Neptune s atmosphere at the 0.1 bar level is T = 55 K = — 218 °C = — 361 °F [65], Since Eq. (14) was derived for standard conditions (lbar atmospheric pressure on Earth), its accuracy may be reduced if it is applied at the 0.1 bar level on Neptune. If we nevertheless apply it at the 0.1 bar level on Neptune, we obtain, even with a slow (by Neptune standards) V = 50 mi / h wind, W = -544 °F = -320 °C = -47 K. 

The standard wind-chill formula [Eq. (14)] should not be confused with the standard wind-chill table [66], The standard wind-chill table is based on a standard of calm of 3 mi / h (typical walking speed), rather than on the true standard of calm V = 0 mi / h in true accordance with the standard wind-chill formula [Eq. (14)] that we adopt in this Sect. 4.2. Also, the recommended ranges of applicability of the standard wind-chill table are —50°F < T < 50°F and 3mi/h < V < 110mi /h [66], But we base our calculations of W on the standard wind-chill formula [Eq. (14)], for which no limits on the range of applicability are stated for either T or V [66]. If there is a sufficiently strong wind on Neptune, then Eq. (14) yields a cold negative Kelvin effective wind-chill temperature VV. 

Re Entries [66] and [67], Refs. [66] and [67]) An online brochure accessible at Ref. [66] provides more information. Reference [67] augments Ref. [66] with still more information, including references and a few alternative formulas for wind-chill temperature W. (In Australia the wind-chill temperature >V is dubbed as the apparent temperature AT.) In this Sect. 4.2. we always calculate W based on the formula employed by the U. S. A. National Weather Service [Eq. (14)]. 

It has been argued [83], that Eq. (14) for wind-chill temperature W is only an approximation [83], that even as an approximation it is valid only at Earth-like or "human"... 

See the Wikipedia article entitled "Wind chill." [Internet], 2015. Available from ... 

We are familiar with the cooling effect of wind and rain on our own exposed skin weather forecasters refer to the wind chill factor . The data in Table 5.1 shows the effectiveness of water sprays in removing heat from the surface of extruded plastic pipes. Consequently, the pipe cooling rate is limited by the transient conduction within the plastic the melt surface can be treated as if kept at the water temperature, and the analysis of the last section be used. 

Whereas the Humidex accounts for the effect of humidity on how the body perceives temperatures above 20 °C, the wind chill factor accounts for the enhanced cooling effect caused by wind. The sensation of temperature depends... 

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