# PBS Teachers™

 Weather: Wind Chill (Grades 8-10) One of the most prevalent aspects of current weather reporting is the inclusion of the wind chill factor each day, particularly in the northern climates during the winter. Wind chill factors are supposed to measure the effect of the combination of temperature and wind speed on human comfort. Remember that these factors do not have the same effect on inanimate objects, or even on other animals or plants. Nor is this effect felt by humans who are sheltered from the wind. One formula for determining the wind chill factor in degrees Fahrenheit can be found at http://ourworld.compuserve.com/homepages/Gene_Nygaard/windchil.htm and is: Twc = (0.3V0.5 + 0.474 - 0.02V)(T - 91.4) + 91.4 Twc is the wind chill, V is the wind speed in statute miles per hour, and T is the temperature in degrees Fahrenheit. In a formula to calculate a Celsius wind chill, V would be the wind speed in kilometers per hour, and T would be the temperature in degrees Celsius.   1. Using the formula compute the Fahrenheit wind chill for a wind speed of 5 mph and a temperature of 10 °F. 2. If the wind chill reading were –20 °F and the wind speed were 10 mph, determine the temperature in degrees Fahrenheit. 3. Explain how the formula for Fahrenheit wind chill could be changed to create a formula for Celsius wind chill. Use your explanation to create your own formula for Celsius wind chill. According to the source above, a formula for Celsius wind chill is: T(wc) = 0.045(5.27V0.5 + 10.45 - 0.28V) (T - 33) + 33 Remember, V is the wind speed in kilometers per hour, and T the temperature in degrees Celsius. 4. Compare the results of using the formula you created to the results from the given formula for determining Celsius wind chill. What might cause any differences. © 1995 - 2013 Public Broadcasting Service (PBS).