Weather Software > Station Software Development

Wet Bulb Globe Temperature

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Wet Bulb Globe Temperature (WBGT) is an important indicator of heat stress and is used by the military, sports and occupational health authorities. More info here: https://en.wikipedia.org/wiki/Wet-bulb_globe_temperature.

It needs a black globe thermometer to be measured accurately as it takes into account solar radiation, sun position and wind speed as well as temperature and humidity. I have tried to create a program in python to simulate WBGT using standard weather station data. The main source for the maths is here: https://www.weather.gov/media/tsa/pdf/WBGTpaper2.pdf. (I don't pretend to understand all the maths!)

--- Code: ---import math
from math import log
from math import atan
from math import exp
from math import cos

# Temperature in °C
# Humidity in %
# Pressure Sea Level in mbars
# WindSpeed in Km/h
# SunAltitude in degrees above horizon
# Cloudcover in %

# Enter the data
Temperature = 29.7
Humidity = 27
Pressure = 1014
WindSpeed = 0
SunAltitude = 45
Cloudcover = 0

T = Temperature
RH = Humidity
P = Pressure
W = WindSpeed
Alt = SunAltitude
f = Cloudcover

u = W * 1000
if u == 0:
u = 500

a = 17.368
b = 238.88
g = log(RH/100) + ((a*T)/(b+T))

# Calculate Dew Point DP
DP = (b * g)/(a-g)

# Calculate Wet Bulb WB
WB = T * atan(0.151977 * (RH + 8.313659)**0.5) + atan(T + RH) - atan(RH - 1.676331) + 0.00391838 * RH**1.5 * atan(0.023101 * RH) - 4.686035

ea = exp(17.67 * (DP - T)/(DP + 243.5)) * (1.0007 + 0.00000346 * P) * 6.112 * exp(17.502 * T / (240.97 + T))
eb = 0.575 * ea**0.142857
fdif = (100 - f)/100
fdb = 1 - fdif
B = S * ((fdb / ((4*(5.67*10**-8)) * cos(z))) + (1.2/(5.67*10**-8)) * fdif) + eb * T**4
C = (0.315*u**0.58)/(5.3865*10**-8)

# Calculate Globe Temperature GT
GT = (B + C * T + 7680000)/(C+256000)

# Calculate Wet Bulb Globe Temperature WBGT
WBGT = 0.7*WB + 0.2*GT + 0.1*T
print(round(WBGT, 2))

--- End code ---

Has anybody else tried to do this?

The program is running live on my site using my own data (in the Temperature box)

http://moonappreciationsociety.com/Meteo/VillarPerosa/index.php

SteveFitz1:
I created a WBGT page on my site a couple of years ago using PHP. You can see my page here:
https://www.tylertexasweather.com/wbgtforecast.htm

I use a page on the NWS site to compare my results to. They are very close.
https://www.weather.gov/tsa/wbgt

Steve

Thanks Steve

What are you using to calculate WBGT?

Can you share the code?

SteveFitz1:
Check your messages. I sent you a couple of PMs.

Steve