double RelativeHumidity = 32;
double TemperatureInC = 7.170000;
double SolarRadiationInWSquareMeter = 174;
double WaterVapourPressure = RelativeHumidity / 100 * 6.105 * Math.Exp(17.27 * TemperatureInC / (237.7 + TemperatureInC));
double WindSpeedMetersPerSecond = 0;
double ApparentTemperature_NonRadiation = TemperatureInC + (0.33 * WaterVapourPressure) - (0.70 * WindSpeedMetersPerSecond) - 4;
double ApparentTemperature_Radiation = TemperatureInC + (0.348 * WaterVapourPressure) - (0.70 * WindSpeedMetersPerSecond) + (0.70 * (SolarRadiationInWSquareMeter / (WindSpeedMetersPerSecond + 10))) - 4.25;
I have taken the formula from
http://www.bom.gov.au/info/thermal_stress/In my case it is quite cold, 7.17C
The first method ApparentTemperature_NonRadiation returns 4.23C
The second method ApparentTemperature_Radiation returns 16.22C (so I have a problem here)
The only difference in the formulas are
0.70×Q/(ws + 10)
Q = Net radiation absorbed per unit area of body surface (w/m2)
My Solar is 177 at the moment (not a very strong day) so does that mean Q = 177?
If there is no wind speed then that would be
0.70 * 174= 121.8
Now 121.8 / (ws + 10) = 12.18f ws = 0 (no wind)
Well we can not add 12.18C to the temperature
Can anyone spot my problem?
Here is the original formula
The formula for the AT used by the Bureau of Meteorology is an approximations of the value provided by a mathematical model of heat balance in the human body.
It can include the effects of temperature, humidity, wind-speed and radiation. Two forms are given, one including radiation and one without.
On this site we use the non-radiation version.
Version including the effects of temperature, humidity, and wind:
AT = Ta + 0.33×e − 0.70×ws − 4.00
Version including the effects of temperature, humidity, wind, and radiation:
AT = Ta + 0.348×e − 0.70×ws + 0.70×Q/(ws + 10) − 4.25
where:
Ta = Dry bulb temperature (°C)
e = Water vapour pressure (hPa) [humidity]
ws = Wind speed (m/s) at an elevation of 10 meters
Q = Net radiation absorbed per unit area of body surface (w/m2)
The vapour pressure can be calculated from the temperature and relative humidity using the equation:
e = rh / 100 × 6.105 × exp ( 17.27 × Ta / ( 237.7 + Ta ) )
where:
rh = Relative Humidity [%]
Source: Norms of apparent temperature in Australia, Aust. Met. Mag., 1994, Vol 43, 1-16