### Author Topic: Wet Bulb Globe Temperature  (Read 499 times)

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#### marshad

• Member
• • Posts: 17 ##### Wet Bulb Globe Temperature
« on: July 17, 2021, 08:35:19 AM »
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: [Select]
`import mathfrom math import logfrom math import atanfrom math import expfrom math import cosfrom math import radians# Temperature in °C# Humidity in %# Pressure Sea Level in mbars# WindSpeed in Km/h# SolarRad in w/m3# SunAltitude in degrees above horizon# Cloudcover in %# Enter the dataTemperature = 29.7Humidity = 27Pressure = 1014WindSpeed = 0SolarRad = 780SunAltitude = 45Cloudcover = 0T = TemperatureRH = HumidityP = PressureW = WindSpeedS = SolarRadAlt = SunAltitudef = Cloudcoveru = W * 1000if u == 0:    u = 500z = radians(90 - Alt)a = 17.368b = 238.88g = log(RH/100) + ((a*T)/(b+T))# Calculate Dew Point DP DP = (b * g)/(a-g)# Calculate Wet Bulb WBWB = 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) - 4.686035ea = 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**0.142857fdif = (100 - f)/100fdb = 1 - fdifB = S * ((fdb / ((4*(5.67*10**-8)) * cos(z))) + (1.2/(5.67*10**-8)) * fdif) + eb * T**4C = (0.315*u**0.58)/(5.3865*10**-8)# Calculate Globe Temperature GTGT = (B + C * T + 7680000)/(C+256000)# Calculate Wet Bulb Globe Temperature WBGTWBGT = 0.7*WB + 0.2*GT + 0.1*Tprint(round(WBGT, 2))`
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 ##### Re: Wet Bulb Globe Temperature
« Reply #1 on: July 17, 2021, 08:55:56 AM »
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

#### marshad

• Member
• • Posts: 17 ##### Re: Wet Bulb Globe Temperature
« Reply #2 on: July 17, 2021, 12:37:33 PM »
Thanks Steve

What are you using to calculate WBGT?

Can you share the code?

#### SteveFitz1 ##### Re: Wet Bulb Globe Temperature
« Reply #3 on: July 18, 2021, 11:39:51 AM »
Check your messages. I sent you a couple of PMs.

Steve

#### marshad

• Member
• • Posts: 17 ##### Re: Wet Bulb Globe Temperature
« Reply #4 on: July 19, 2021, 07:55:20 AM »
Check your messages. I sent you a couple of PMs.

Steve

Thanks -have responded.