Author Topic: Feels like  (Read 448 times)

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Offline Jáchym

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Feels like
« on: January 23, 2017, 07:26:39 PM »
Some time ago we were discussing the feels like (apparent) temperature here and the accuracy of various formulas used to calculate it.... I mentioned that the debate is basically irrelevant because it is impossible to calculate the way it is normally done - i.e. using air temperature, humidity, wind and a few other parameters in rare cases. I also mentioned that the real way of doing this is absolutely impossible to apply in practice.

Just today I was actually dealing with this at work and I just want to show you what the real formula looks like :D

The basis of this is the energy balance equation:

M+W+R+C+ED+ERe+ESw+S= 0

Where, M: the metabolic rate (internal energy production), W the physical work output, R the net radiation of the body, C the convective heat flow, ED the latent heat flow to evaporate water diffusing through the skin (imperceptible perspiration), ERe the sum of heat flows for heating and humidifying the inspired air, ESw the heat flow due to evaporation of sweat, and S the storage heat flow for heating or cooling the body mass.

The individual heat flows are controlled by the following meteorological parameters:

• air temperature: C, ERe
• air humidity: ED, ERe, ESw
• wind velocity: C, ESw
• radiant temperature: R

Thermo-physiological parameters are required in addition:
• heat resistance of clothing (clo units) and
• activity of humans (in W).

So just in case some of you want to argue about the accuracy of the "normally used" equations (by NOAA etc.), and argue that one differs by 0.1 degree from the other one.... remember the above formula :D If you really want to give it a try then all I can say is good luck :D And also remember that some of the parameters are uniqe for every person so in the best case you will come up with a unique formula for yourself or some other one person :D

 

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