What is the wind chill index?

Wind chill index is an index that indicates the relationship between human heat loss and wind speed and temperature when the temperature is lower than 15℃.

Wind chill index is a physical quantity representing the relationship between wind speed and cooling. Experiments show that when the air temperature is-1 and 1℃, if the wind speed is 1 1 and 1 m/s (about level 6), people will feel the temperature equivalent to-17 and 2℃ when there is no wind. If the wind speed is as high as 15, 6 m/s (about magnitude 7), it is equivalent to the cold degree of -2℃ when there is no wind. It can be seen that people feel lower than the actual temperature in the cold wind.