ACE3/addons/weather/functions/fnc_calculateWetBulb.sqf
2016-01-05 01:39:29 -06:00

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/*
* Author: Ruthberg
* Calculates wet bulb based on temperature and relative humidity
*
* Arguments:
* 0: temperature - degrees celsius <NUMBER>
* 1: pressure - hPa <NUMBER>
* 2: relativeHumidity - value between 0.0 and 1.0 <NUMBER>
*
* Return Value:
* wet bulb <NUMBER>
*
* Example:
* [0, 1020, 0.5] call ace_weather_fnc_calculateWetBulb
*
* Public: No
*/
#include "script_component.hpp"
params ["_temperature", "_pressure", "_relativeHumidity"];
// Source: http://cosmoquest.org/forum/showthread.php?155366-Calculating-Wet-Bulb-Temperature-from-RH-amp-Dry-Bulb
private _es = 6.112 * exp((17.67 * _temperature) / (_temperature + 243.5));
private _e = _es * _relativeHumidity;
private _eDiff = _es - _e;
private _eGuessPrev = _es;
private _cTempDelta = 3.3145;
private _twGuess = _temperature;
for "_j" from 1 to 50 do {
_twGuess = _twGuess - _cTempDelta;
private _eguess = 6.112 * exp((17.67 * _twGuess) / (_twGuess + 243.5));
_eguess = _eguess - (_pressure * (_temperature - _twGuess) * 0.00066 * (1 + (0.00115 * _twGuess)));
_eDiff = _eguess - _e;
if (abs(_eDiff) <= 0.001) exitWith {};
_cTempDelta = _eDiff / ((_eguessprev - _eguess) / _cTempDelta);
_eguessprev = _eguess;
};
_twGuess