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ethaniel/relative_to_absolute.php

Created November 26, 2021 03:35
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PHP script for converting relative humidity to absolute humidity
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relative_to_absolute.php
<?php
// formulas courtesy of https://planetcalc.com/2167/
$pressure = 1000; // Pressure in hPa
$temperature = 25; // Temperature in Celsius
$humidity = 75; // Relative Humidity in %
$e = 2.71828;
$tp = ($pressure * 133.322)/100;
$et = 6.112 * pow($e,((17.62*$temperature)/(243.12+$temperature)));
$fp = 1.0016 + 3.15 * pow(10,-6) * $tp - 0.074/$tp;
$ept = $fp*$et;
$e = ($humidity/100)*$ept;
$Rv = 461.5;
$T = $temperature + 273.15;
$absolute = ($e*100/($Rv*$T)); // absolute humidity
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