热量指数公式
在阴影位置，热指数是结合了空气温度和相对湿度的温度。出汗或出汗是人体降温的自然方式。汗水蒸发负责带走身体的热量。另一方面，高相对湿度会减慢蒸发速度。当温度为32摄氏度，相对湿度为70%时，热指数等于实际空气温度。
热度指数
热量指数公式是根据温度和相对湿度来表示身体感知的空气温度。大气的实际温度与我们感知或感觉到的温度之间存在差异。
例子
If the temperature is 32°C and 70% relative humidity, the heat index is 41°C. This heat index has an implied humidity of 20%. It’s the value of the relative humidity for which the heat index formula shows 41°C. A heat index temperature of 32°C holds implied relative humidity of 38%.
排汗或出汗是人体通常如何自我冷却的方式。汗水蒸发，带走身体的热量。另一方面，高相对湿度会减慢蒸发速度。结果，身体散热的速度变慢了，给人一种过热的感觉。这种影响是主观的，不同的人因各种原因（例如体型差异、代谢差异、水合作用差异、怀孕、更年期、药物作用和/或药物戒断）而对热量的感知不同；它的测量是基于对给定温度和湿度下人们感觉有多热的主观描述。结果，计算出热量指数，将一种温度和湿度组合与另一种进行比较。
公式
热指数公式表示为，
HI = c1 + c2T + c3R + c4TR + c5T2 + c6R2 + c7T2R + c8TR2 + c9T2R2
where,
- HI denotes the heat index in degrees Fahrenheit
- R denotes the relative humidity
- T refers to the temperature in °F
- c1 = −42.379
- c2 = −2.04901523
- c3 = −10.14333127
- c4 = −0.22475541
- c5 = −6.83783 × 10−3
- c6 = −5.481717 × 10−2
- c7 = −1.22874 × 10−3
- c8 = 8.5282 × 10−4
- c9 = −1.99 × 10−6
热指数函数
它用于模拟人体对湿度和热量的感觉，以产生保护人和动物的健康或公共程序。在这种环境中暴露在阳光下的部件的热指数可能更高或更低。此外，从事各种活动的人可能对热量的感觉不同，并且可能感觉不到当天或地点测量的热量指数。
示例问题
问题 1. 计算温度为 185° F 和 86% 相对湿度的热指数。
解决方案：
Given: T = 185° F and R = 86%.
Since, HI = c1 + c2T + c3R + c4TR + c5T2 + c6R2 + c7T2R + c8TR2 + c9T2R2
Substituting the given values in the above formula, we have:
HI = -42.379 + -2.04901523 × 185 + -10.14333127 × 86 + -0.22475541 × 185 × 86 + -6.83783 × 10−3 × (185)2+-5.481717 × 10−2 × (86)2+ -1.22874 × 10−3 × (185)2 × 86 + 8.5282 × 10−4 × 185 × (86)2 + -1.99 × 10−6 × (185)2 × (86)2
HI = 1274° F
问题 2. 计算温度为 90° F 和 60% 相对湿度的热指数。
解决方案：
Given: T = 90° F and R = 60%.
Since, HI= c1 + c2T + c3R + c4TR + c5T2 + c6R2 + c7T2R + c8TR2 + c9T2R2
Substituting the given values in the above formula, we have:
HI = -42.379 + -2.04901523 x 90 + -10.14333127 x 60 + -0.22475541 x 90 x 60 + -6.83783 x 10−3 x (90)2+-5.481717 x 10−2 x (60)2+ -1.22874 x 10−3 x (90)2× 60 + 8.5282 x 10−4 x 90 x (60)2 + -1.99 x 10−6 x (90)2 x (60)2
HI = 100° F
问题3、为什么热指数比实际温度高？
解决方案：
The heat index is a measurement of how hot it really feels when the relative humidity is incorporated with the actual temperature. Heat indices were designed for use in the shade with light wind conditions. If in direct sunlight, the heat index can increase as much as 15 degrees. With very hot and dry air, strong winds can also be extremely dangerous. When a human being perspires, the water in his or her sweat evaporates. … When humidity is high, the rate of evaporation and cooling is reduced, resulting in it feeling hotter than it actually is.
问题4.热指数可以低于实际温度吗？
解决方案：
It most certainly is, and it occurs when high temperatures are combined with low dew points. Despite the fact that the desert is incredibly hot, the heat index is lower than the temperature due to dry conditions. In 2017, the temperature in Phoenix hit 119 degrees, while the dew point was just 37. This resulted in a relative humidity of 6% and a heat index of 111, which was still deadly but eight degrees lower than the temperature. Chicago’s highest heat index occurred during the city’s catastrophic 1995 heat wave, when a 106-degree temperature at Midway Airport coupled with a suffocating 81-degree dew point to produce a heat index of 125. Dhahran, Saudi Arabia, had the world’s highest heat index of 178, with a temperature of 108 and a dew point of 95.
问题五、为什么测热指数时不考虑风速？
解决方案：
All weather agencies record ‘ambient temperature’— how warm the air is in the shade and sheltered from the wind. This is done by placing weather recording instruments in a Stevenson Screen. The height above ground that Stevenson Screens are placed is between 1.25 and 2 m (4 ft. 1 in and 6 ft. 7 in). By using this approach weather readings from around the world can be regarded being consistent and relatable.
When weather forecasters produce a temperature forecast they try to produce a number that will be similar to what would be recorded by instruments in a Stevenson Screen.
Knowing the effect humidity and wind has on how humans feel temperature most weather agencies also try to forecast the apparent temperature. In colder parts of the world, agencies issue the forecast temperature and the wind chill factor. This isn’t generally done for warmer regions, partly because predicting wind speeds and wind consistency can be difficult.