Dieses PHP-Script berechnet die Taupunkt-Temperatur. Eingabewert ist die Temperatur (in °C) sowie die Luftfeuchte (in %).
Der $nil-Wert bestimmt den Wert der zurückgegeben werden soll, wenn die Berechnung scheitert. Das ist beispielsweise dann der Fall, wenn schon die Eingabewerte Fehler beinhalten.
<?php
/*
This Software calculates dewpoint by given 2m-temperature and 2m-humidity.
Copyright (C) 2020 Guido Richter / tintenkobold.de
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License [http://www.gnu.org/licenses/] for more details.
*/
function tp($nil,$t2m,$rh2m)
{
if($rh2m>0 AND is_numeric($t2m))
{
// calculate dewpoint
$saturation_pressure = 6.1078*pow(10,((7.5*$t2m)/(237.3+$t2m)));
$saturation_deficit = ($rh2m/100)*$saturation_pressure;
$dp = (234.67*(log($saturation_deficit)/log(10))-184.2)/(8.233-(log($saturation_deficit)/log(10)));
return $dp;
}
else return $nil;
}
?>