ACE3/addons/advanced_ballistics/functions/fnc_calculateAirDensity.sqf

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/*
* Author: Ruthberg
*
* Displays a wind info (colored arrow) in the top left corner of the screen
*
* Arguments:
* 0: temperature - degrees celcius <NUMBER>
* 1: pressure - hPa <NUMBER>
* 2: relativeHumidity - value between 0.0 and 1.0 <NUMBER>
*
* Return Value:
* 0: density of air - kg * m^(-3) <NUMBER>
*
* Return value:
* None
*/
#include "script_component.hpp"
private ["_temperature", "_pressure", "_relativeHumidity"];
_temperature = _this select 0; // in C
_pressure = _this select 1; // in hPa
_relativeHumidity = _this select 2; // as ratio 0-1
_pressure = _pressure * 100;
if (_relativeHumidity > 0) then {
private ["_pSat", "_vaporPressure", "_partialPressure"];
// Saturation vapor pressure calculated according to: http://wahiduddin.net/calc/density_algorithms.htm
_pSat = 6.1078 * 10 ^ ((7.5 * _temperature) / (_temperature + 237.3));
_vaporPressure = _relativeHumidity * _pSat;
_partialPressure = _pressure - _vaporPressure;
(_partialPressure * DRY_AIR_MOLAR_MASS + _vaporPressure * WATER_VAPOR_MOLAR_MASS) / (UNIVERSAL_GAS_CONSTANT * KELVIN(_temperature))
} else {
_pressure / (SPECIFIC_GAS_CONSTANT_DRY_AIR * KELVIN(_temperature))
};