Dewpoint

dewpoint.js

function dewpoint(tempCelsius, relHumidity) {
    const a = tempCelsius < 0 ? 7.6 : 7.5
    const b = tempCelsius < 0 ? 240.7 : 237.3
    const sdd = 6.1078 * Math.pow(10, (a * tempCelsius) / (b + tempCelsius))
    const dd = relHumidity / 100 * sdd
    const v = Math.log10(dd / 6.1078)
    const dewPointCelsius = b * v / (a - v)
    return dewPointCelsius
}

dewpoint.py

from math import log10

def dewpoint(temp_celsius, rel_hum):
    a = 7.6 if temp_celsius < 0 else 7.5
    b = 240.7 if temp_celsius < 0 else 237.3
    sdd = 6.1078 * 10**((a * temp_celsius) / (b + temp_celsius))
    dd = rel_hum / 100.0 * sdd
    v = log10(dd / 6.1078)
    dewpoint_celsius = b * v / (a - v)
    return dewpoint_celsius