Ask Anything: Wind Chill? Heat Index? Can't We Combine Them?
Wind chill? Head index? Fred Zhang/Getty Images More than 100 weather indices have been proposed over the past century in an effort to translate environmental conditions—how cold it is, how windy, how sunny, how wet—into felt experience and physiological risk. Many of these, like the wind chill and the heat index, focus on specific subsets of the variables in play. (The wind chill uses ambient temperature and wind speed; the heat index uses temperature and humidity.) But in the past few years, a group of 45 scientists from 23 countries, led by German meteorologist Gerd Jendritzky, devised what they call the Universal Thermal Climate Index (UTCI)—a simple, single-number weather reading that could estimate how an average person would feel when faced with the elements. Such an index would come in handy for researchers who wanted to compare weather-related stress and mortality...