In recent days, discussions about the heat index have gained attention. This metric attempts to quantify how hot the air feels, factoring in both temperature and humidity.
The heat index often registers higher than the actual temperature, sometimes by a significant margin. For instance, at one moment in Central Park, while the temperature read 98°F, the heat index climbed to 105°F. This disparity occurs because humidity hampers perspiration evaporation, making it feel warmer.
What is the Heat Index?
The heat index is an extension of the saying, “it’s not the heat, it’s the humidity.” The calculation involves a complex formula:
(T × 2.049) + (H × 10.143) – (T × H × 0.225) – (T² × 0.007) – (H² × 0.055) + (T² × H × 0.001) + (H² × T × 0.001) – (T² × H² × 0.000002) – 42.379
Here, T represents temperature and H is relative humidity. This equation helps estimate the perceived temperature when these factors combine.
The Origin of the Heat Index
Lans Rothfusz, a retired meteorologist from the National Weather Service, devised the heat index formula. He created it in 1990 during his time as an intern at the Weather Service’s Southern Region Headquarters in Fort Worth.
Rothfusz, who once referred to himself as a “punk intern,” received recognition for his contributions, including the National Weather Association’s operational achievement award in 2014.
The heat index remains a valuable tool in understanding weather conditions and preparing for extreme heat, affecting how people perceive and react to high temperatures.
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