Further Information On The Role Of Water Vapor In Measuring Heat By Francis Massen

In response to my post Comment On The Northeast Heat Wave, Francis Massen has sent the e-mail below which he graciously has permitted us to post here.
Dear Roger,

Concerning your comments on the importance of moist enthalpy I would point your attention to my website and the on-line sensor measuring the WBGT (Wet bulb Globe Temperature  = heatstress):
http://meteo.lcd.lu/today_09.png

I make these measurements for the medical service of Luxembourg’s army, whose garrison is also located at Diekirch. The WBGT is measured by 3 thermometers:

W = wet bulb temperature (natural ventilation, not forced ventilation as  found in psychrometers)
G = temperature inside a black painted sphere
T = dry thermometer temperature

WBGT is defined as: WBGT = 0.7*W + 0.2*G + 0.1*T

If WGCT > 32°C, all heavy work and exercises should be avoided, according to army instructions.

The graph given in the link above is interesting for it shows how  different these 3 temperatures often are.

There is a paper on these measurements in French here:
http://meteo.lcd.lu/papers/wbgt/ambiance_chaude.html

Best regards,

Francis

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Francis Massen
Laboratoire de Physique et meteoLCD
Lycée Classique de Diekirch
32 av. de la gare
L-9233 Diekirch
http: //meteo.lcd.lu
http: //computarium.lcd.lu
http: //bmb.lcd.lu