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heat index with refinements from NWS for lower values

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Frankie 2020-04-02 11:28:58 +01:00
parent 428e115b57
commit f681b8e861
1 changed files with 14 additions and 2 deletions
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16
DHT.cpp
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@ -175,9 +175,12 @@ float DHT::computeHeatIndex(bool isFahrenheit) {
} }
/*! /*!
* @brief Compute Heat Index * @brief Compute Heat Index (based on Robert G. Steadman tables)
* Using both Rothfusz and Steadman's equations * Using Rothfusz equations with refinements by the NWS
* (http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml) * (http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml)
* and NWS algorithm that respects lower values of temperature
* and humidity
* (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3801457/)
* @param temperature * @param temperature
* temperature in selected scale * temperature in selected scale
* @param percentHumidity * @param percentHumidity
@ -193,6 +196,15 @@ float DHT::computeHeatIndex(float temperature, float percentHumidity,
if (!isFahrenheit) if (!isFahrenheit)
temperature = convertCtoF(temperature); temperature = convertCtoF(temperature);
if(temperature <= 40) {
return isFahrenheit ? temperature : convertFtoC(temperature);
}
float varA = -10.3 + 1.1 * temperature + 0.047 * percentHumidity;
if (varA < 79) {
return isFahrenheit ? varA : convertFtoC(varA);
}
hi = 0.5 * (temperature + 61.0 + ((temperature - 68.0) * 1.2) + hi = 0.5 * (temperature + 61.0 + ((temperature - 68.0) * 1.2) +
(percentHumidity * 0.094)); (percentHumidity * 0.094));