Created
August 8, 2016 10:57
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Arduino dewpoint calculation
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| // reference: http://wahiduddin.net/calc/density_algorithms.htm | |
| double computeDewPoint2(double celsius, double humidity) | |
| { | |
| double RATIO = 373.15 / (273.15 + celsius); // RATIO was originally named A0, possibly confusing in Arduino context | |
| double SUM = -7.90298 * (RATIO - 1); | |
| SUM += 5.02808 * log10(RATIO); | |
| SUM += -1.3816e-7 * (pow(10, (11.344 * (1 - 1/RATIO ))) - 1) ; | |
| SUM += 8.1328e-3 * (pow(10, (-3.49149 * (RATIO - 1))) - 1) ; | |
| SUM += log10(1013.246); | |
| double VP = pow(10, SUM - 3) * humidity; | |
| double T = log(VP/0.61078); // temp var | |
| return (241.88 * T) / (17.558 - T); | |
| } | |
| // delta max = 0.6544 wrt dewPoint() | |
| // 5x faster than dewPoint() | |
| // reference: http://en.wikipedia.org/wiki/Dew_point | |
| double dewPointFast(double celsius, double humidity) | |
| { | |
| double a = 17.271; | |
| double b = 237.7; | |
| double temp = (a * celsius) / (b + celsius) + log(humidity*0.01); | |
| double Td = (b * temp) / (a - temp); | |
| return Td; | |
| } |
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